Photoacoustic-computed tomography is a novel imaging technique that combines high absorption contrast and deep tissue penetration capability,enabling comprehensive three-dimensional imaging of biological targets.Howev...Photoacoustic-computed tomography is a novel imaging technique that combines high absorption contrast and deep tissue penetration capability,enabling comprehensive three-dimensional imaging of biological targets.However,the increasing demand for higher resolution and real-time imaging results in significant data volume,limiting data storage,transmission and processing efficiency of system.Therefore,there is an urgent need for an effective method to compress the raw data without compromising image quality.This paper presents a photoacoustic-computed tomography 3D data compression method and system based on Wavelet-Transformer.This method is based on the cooperative compression framework that integrates wavelet hard coding with deep learning-based soft decoding.It combines the multiscale analysis capability of wavelet transforms with the global feature modeling advantage of Transformers,achieving high-quality data compression and reconstruction.Experimental results using k-wave simulation suggest that the proposed compression system has advantages under extreme compression conditions,achieving a raw data compression ratio of up to 1:40.Furthermore,three-dimensional data compression experiment using in vivo mouse demonstrated that the maximum peak signal-to-noise ratio(PSNR)and structural similarity index(SSIM)values of reconstructed images reached 38.60 and 0.9583,effectively overcoming detail loss and artifacts introduced by raw data compression.All the results suggest that the proposed system can significantly reduce storage requirements and hardware cost,enhancing computational efficiency and image quality.These advantages support the development of photoacoustic-computed tomography toward higher efficiency,real-time performance and intelligent functionality.展开更多
Rock brittleness is a critical property in geotechnical and energy engineering,as it directly influences the prediction of rock failure and stability assessment.Although numerous methods have been developed to evaluat...Rock brittleness is a critical property in geotechnical and energy engineering,as it directly influences the prediction of rock failure and stability assessment.Although numerous methods have been developed to evaluate brittleness,many fail to comprehensively account for the impacts of microstructural changes,mineralogical characteristics,and stress conditions on energy evolution during failure.This study proposes a novel approach for brittleness evaluation based on the energy evolution throughout the post-peak failure process,integrating two micromechanical mechanisms:crack propagation and frictional sliding.A new brittleness index is defined as the ratio of generated surface energy to released elastic energy,providing a unified framework for assessing both Class I and Class II mechanical behaviors.The brittleness of cyan,white,and gray sandstones was investigated under various confining pressures and moisture conditions using X-ray diffraction(XRD),scanning electron microscopy(SEM),and conventional triaxial compression(CTC)tests.The results demonstrate that brittleness decreases with increasing confining pressure,due to suppressed crack propagation,and increases under saturated conditions,as moisture enhances crack propagation.By establishing connections between mineral composition,microstructural features,and stress-induced responses,the proposed method overcame limitations of previous approaches and offered a more precise tool for evaluating rock brittleness under diverse environmental scenarios.展开更多
An in-depth understanding of the behaviours of solid propellants under low-velocity impact loads is crucial for enhancing their safety in applications such as aerospace propulsion.This study investigated the dynamic r...An in-depth understanding of the behaviours of solid propellants under low-velocity impact loads is crucial for enhancing their safety in applications such as aerospace propulsion.This study investigated the dynamic responses of single ammonium perchlorate(AP)/octogen(HMX)particles embedded in a hydroxyl-terminated polybutadiene(HTPB)binder under dynamic compression loading via real-time synchrotron-based X-ray phase contrast imaging and a modified split Hopkinson pressure bar(SHPB)system.The compression of the viscoelastic binder and subsequent dynamic fracturing of the AP/HMX particles were captured.During compression,transverse cracks developed within the AP particles,and their propagation led to particle fracturing,resulting in ductile fracturing.Unlike AP,HMX generated numerous short cracks within the internal and edge regions simultaneously,leading to fragmentation and brittle fracturing.Moreover,particle damage reduced the modulus of the sample,shifting its dynamic stress response from nonlinear elasticity to strain softening and further strain hardening as the binder exhibited plastic deformation.A compression simulation incorporating a real particle microscopic structure was established to study the mechanical response of the interface and particles.The simulation results agreed with the experimental observations.These results indicate that the shear stress at the HTPB-AP interface is greater than that at the HTPB-HMX interface,which is a factor influencing the differences in the mesoscale damage mechanisms of the particles.展开更多
Large language models(LLMs)have revolutionized AI applications across diverse domains.However,their widespread deployment has introduced critical security vulnerabilities,particularly prompt injection attacks that man...Large language models(LLMs)have revolutionized AI applications across diverse domains.However,their widespread deployment has introduced critical security vulnerabilities,particularly prompt injection attacks that manipulate model behavior through malicious instructions.Following Kitchenham’s guidelines,this systematic review synthesizes 128 peer-reviewed studies from 2022 to 2025 to provide a unified understanding of this rapidly evolving threat landscape.Our findings reveal a swift progression from simple direct injections to sophisticated multimodal attacks,achieving over 90%success rates against unprotected systems.In response,defense mechanisms show varying effectiveness:input preprocessing achieves 60%–80%detection rates and advanced architectural defenses demonstrate up to 95%protection against known patterns,though significant gaps persist against novel attack vectors.We identified 37 distinct defense approaches across three categories,but standardized evaluation frameworks remain limited.Our analysis attributes these vulnerabilities to fundamental LLM architectural limitations,such as the inability to distinguish instructions from data and attention mechanism vulnerabilities.This highlights critical research directions such as formal verification methods,standardized evaluation protocols,and architectural innovations for inherently secure LLM designs.展开更多
Background:Penile augmentation through injectable substances is becoming increasingly common.A growing number of aesthetic clinics are developing penile enlargement procedures using various injectable materials.Althou...Background:Penile augmentation through injectable substances is becoming increasingly common.A growing number of aesthetic clinics are developing penile enlargement procedures using various injectable materials.Although these procedures are now performed in more controlled and medically supervised environments,their long-term outcomes remain poorly understood.The promotion of such medical treatments contributes to an increasing interest among adult males in self-injection as a method to alleviate psychological distress associated with penile size concerns.At the same time,access to injectable substances through unofficial or unregulated sources has become increasingly easy.Tor our knowledge,we report the first documented case of self-injection with Garamycin®(gentamicin)cream,contributing to the literature on the often multidisciplinary management of penile enlargement injections,a field still lacking well-established guidelines.Case Description:This case report describes a young patient who self-injected Garamycin®into the penis for the purpose of enlargement.He presented to our urology department with worsening symptoms,including severe and poorly tolerated pain.His primary request was prompt relief of pain while preserving,as much as possible,the aesthetic appearance and functional integrity of his penis.This case required a multi-stage surgical approach to salvage the penis and preserve both its structural integrity and functional outcome.Conclusions:To our knowledge,this case report documents the first reported instance of Garamycin®injection performed for the purpose of penile enlargement.It provides insight into the clinical course of such penile cream injections,demonstrates that a two-stage scrotal flap can achieve both functional and aesthetic outcomes,and highlights the importance of comprehensive management particularly addressing the traumatic impact of penile deformity secondary to inflammation and/or infection,as well as the body dysmorphic concerns often associated with these cases.展开更多
To investigate the damage evolution caused by stress-driven and sub-critical crack propagation within the Beishan granite under multi-creep triaxial compressive conditions,the distributed optical fiber sensing and X-r...To investigate the damage evolution caused by stress-driven and sub-critical crack propagation within the Beishan granite under multi-creep triaxial compressive conditions,the distributed optical fiber sensing and X-ray computed tomography were combined to obtain the strain distribution over the sample surface and internal fractures of the samples.The Gini and skewness(G-S)coefficients were used to quantify strain localization during tests,where the Gini coefficient reflects the degree of clustering of elements with high strain values,i.e.,strain localization/delocalization.The strain localization-induced asymmetry of data distribution is quantified by the skewness coefficient.A precursor to granite failure is defined by the rapid and simultaneous increase of the G-S coefficients,which are calculated from strain increment,giving an earlier warning of failure by about 8%peak stress than those from absolute strain values.Moreover,the process of damage accumulation due to stress-driven crack propagation in Beishan granite is different at various confining pressures as the stress exceeds the crack initiation stress.Concretely,strain localization is continuous until brittle failure at higher confining pressure,while both strain localization and delocalization occur at lower confining pressure.Despite the different stress conditions,a similar statistical characteristic of strain localization during the creep stage is observed.The Gini coefficient increases,and the skewness coefficient decreases slightly as the creep stress is below 95%peak stress.When the accelerated strain localization begins,the Gini and skewness coefficients increase rapidly and simultaneously.展开更多
Objective:To explore the therapeutic effect of double-puncture tympanic membrane puncture and tympanic cavity drug injection in patients with acute secretory otitis media.Methods:A total of 84 patients with acute secr...Objective:To explore the therapeutic effect of double-puncture tympanic membrane puncture and tympanic cavity drug injection in patients with acute secretory otitis media.Methods:A total of 84 patients with acute secretory otitis media admitted to our hospital from June 2024 to June 2025 were selected and randomly divided into two groups by drawing lots.The control group(42 cases)was treated with the traditional single-puncture tympanic membrane puncture and tympanic cavity drug injection method,while the observation group(42 cases)was treated with the double-puncture tympanic membrane puncture and tympanic cavity drug injection method.The therapeutic effects of the two groups were compared.Results:The overall treatment response rate,overall complication rate,time to symptom relief,and improvement in hearing threshold in the observation group were all superior to those in the control group,with statistically significant differences(P<0.05).Conclusion:For acute secretory otitis media,the treatment method of double-puncture tympanic membrane puncture and tympanic cavity drug injection demonstrates definite efficacy,significantly reducing the incidence of complications,accelerating symptom relief,and improving hearing function,making it worthy of promotion.展开更多
In the field of rock engineering,the influence of water is a dynamic process that exhibits varying effects over time and across different locations.To further understand how water influences the mechanical properties ...In the field of rock engineering,the influence of water is a dynamic process that exhibits varying effects over time and across different locations.To further understand how water influences the mechanical properties and acoustic emission(AE)behavior of rocks,this study conducted uniaxial compression experiments on sandstones with varying degrees of wetting under both natural conditions and water-chemical environments.In addition,the study combined AE equipment with digital image correlation(DIC)to monitor the entire failure process.Using the sliding window algorithm,the variation in the variance of AE characteristic parameters during the process of sandstone loading to failure is analyzed from the perspective of critical slowing down.This analysis enables the effective identification of the early warning signal before failure.The experimental findings suggest that an increase in wetting height results in a gradual decrease in peak stress,accompanied by a concomitant increase in the percentage of shear cracks.The characteristic parameters,including energy,amplitude,and ringing count,all exhibit critical slowing phenomena.The waveform of AE characteristic parameters of the same sample is similar,and the mutation time of the precursor signal is roughly the same.All signals appear in the irreversible plastic deformation stage of microcrack initiation.The integration of critical slowing down theory and the b-value early warning method facilitates a more comprehensive evaluation of the stability of rock mass,thereby significantly enhancing the efficiency and safety of disaster prevention measures.展开更多
We present the first systematic experimental validation of return-current-driven cylindrical implosion scaling in micrometer-sized Cu and Al wires irradiated by J-class femtosecond laser pulses.Employing XFEL-based im...We present the first systematic experimental validation of return-current-driven cylindrical implosion scaling in micrometer-sized Cu and Al wires irradiated by J-class femtosecond laser pulses.Employing XFEL-based imaging with sub-micrometer spatial and femtosecond temporal resolution,supported by hydrodynamic and particle-in-cell simulations,we reveal how return current density depends precisely on wire diameter,material properties,and incident laser energy.We identify deviations from simple theoretical predictions due to geometrically influenced electron escape dynamics.These results refine and confirm the scaling laws essential for predictive modeling in high-energy-density physics and inertial fusion research.展开更多
In order to enhance the off-peak performance of gas turbine combined cycle(GTCC)units,a novel collaborative power generation system(CPG)was proposed.During off-peak operation periods,the remaining power of the GTCC wa...In order to enhance the off-peak performance of gas turbine combined cycle(GTCC)units,a novel collaborative power generation system(CPG)was proposed.During off-peak operation periods,the remaining power of the GTCC was used to drive the adiabatic compressed air energy storage(ACAES),while the intake air of the GTCC was heated by the compression heat of theACAES.Based on a 67.3MW GTCC,under specific demand load distribution,a CPG system and a benchmark system(BS)were designed,both of which used 9.388% of the GTCC output power to drive the ACAES.The performance of the CPG and the BS without intake air heating was compared.The results show that the load rate of the GTCC in the CPG system during off-peak periods is significantly enhanced,and the average operating efficiency of the GTCC is increased by 1.19 percentage points.However,in the BS system,due to the single collaborativemethod of load shifting,the GTCC operative efficiency is almost increased by 1.00 percentage points under different ambient temperatures.In a roundtrip cycle at an ambient temperature of 288.15K,the systemefficiency of the CPG reaches 0.5010,which is 0.62 percentage points higher than the operative efficiency of 0.4948 in the standalone GTCC;while the system efficiency of the BS is slightly inferior to that of the standalone GTCC.The findings confirm the technical feasibility and performance improvement of the ACAES-GTCC collaborative power generation system.展开更多
Dual-fuel premixed charge compression ignition (DF-PCCI) combustion has been proven to be a viable alternative to conventional diesel combustion in heavy-duty compression ignition engines due to its low nitrogen oxide...Dual-fuel premixed charge compression ignition (DF-PCCI) combustion has been proven to be a viable alternative to conventional diesel combustion in heavy-duty compression ignition engines due to its low nitrogen oxides (NOx) and particulate matter (PM) emissions. When natural gas (NG) is applied to a DF-PCCI engine, its low reactivity reduces the maximum pressure rise rate under high loads. However, the NG–diesel DF-PCCI engine suffers from low combustion efficiency under low loads. In this study, an injection strategy of fuel supply (NG and diesel) in a DF-PCCI engine was investigated in order to reduce both the fuel consumption and hydrocarbon (HC) and carbon monoxide (CO) emissions under low load conditions. A variation in the NG substitution and diesel start of energizing (SOE) was found to effectively control the formation of the fuel–air mixture. A double injection strategy of diesel was implemented to adjust the local reactivity of the mixture. Retardation of the diesel pilot SOE and a low fraction of the diesel pilot injection quantity were favorable for reducing the combustion loss. The introduction of exhaust gas recirculation (EGR) improved the fuel economy and reduced the NOx and PM emissions below Euro VI regulations by retarding the combustion phasing. The combination of an NG substitution of 40%, the double injection strategy of diesel, and a moderate EGR rate effectively improved the combustion efficiency and indicated efficiency, and reduced the HC and CO emissions under low load conditions.展开更多
·AIM:To evaluate the efficacy and safety of full-thickness sutures combined with intracameral air injection(FTS-AI)versus pre-Descemet’s membrane sutures combined with intracameral air injection(PDS-AI)in the ma...·AIM:To evaluate the efficacy and safety of full-thickness sutures combined with intracameral air injection(FTS-AI)versus pre-Descemet’s membrane sutures combined with intracameral air injection(PDS-AI)in the management of acute corneal hydrops in keratoconus.·METHODS:The research included 8 patients(8 eyes)suffering from acute corneal hydrops caused by keratoconus.Four patients were randomly assigned to FTS-AI.And the other four were randomly assigned to PDS-AI.Corneal oedema,visual acuity,corneal thickness were assessed during follow-up.·RESULTS:The demographics,preoperative duration of symptoms and severity of corneal hydrops between the two groups were not significantly different.The mean corneal oedema resolution time after FTS-AI and PDSAI were 11±1.15 and 15±1.41 d,respectively(P=0.005).The maximum corneal thickness of the scarred region decreased in both groups at one week postoperatively(P<0.05).No obvious difference was found in the mean maximal corneal thickness between the two groups postoperatively.The BCVA improved significantly after FTS-AI and PDS-AI at three months postoperatively.No obvious difference was found in the BCVA after FTS-AI and PDS-AI at three months postoperatively.·CONCLUSION:FTS-AI and PDS-AI are safe and effective therapies to accelerate the resolution of corneal oedema in acute corneal hydrops secondary to keratoconus.Despite faster resolution of corneal oedema in the FTS-AI group,we recommend PDS-AI to avoid potential endothelium cell damage.展开更多
This article analyses numerically the simultaneous influence of the compression rate, fuel nature and the advanced injection of fuel on maximum cylinder pressure during the combustion phrase with the help of the Pytho...This article analyses numerically the simultaneous influence of the compression rate, fuel nature and the advanced injection of fuel on maximum cylinder pressure during the combustion phrase with the help of the Python Spyder calculation code. Indeed, several authors have shown that the combustion of biofuels which make it possible to compensate for fossil and exhaustible resources, presents a cylinder pressure higher by about 3.5% compared to that of conventional diesel D100. This increase in pressure can be reduced by the means of controlling parameters making it possible to preserve the life of the engine and also reduce nitrogen oxides (NOx) and particular matter (PM). This article has two objectives which are: putting in place a numerical tool for the evaluation and simulation of thermal engines and the influence of control parameters on cylinder pressure. The single zone 0D combustion model which considers only the physical phenomena and considers the mixed fuel as a perfect gas is used. The fuel used is the Neem biofuel produced by Doctor Merlin Ayissi of the University of Douala and the D100 diesel fuel. The results are obtained from three fuel injection angles of 20°, 13° and 10° before the TDC (Top Dead Centre) and three values of the engine compression rates of 15, 20 and 25. The delay in combustion is characteristic of the fuel used as illustrated by the cetane number. The results show that the cylinder pressure increases with increasing compression rate and a very high advanced injection. It also shows that the pressure is high when diesel D100 is used instead of D100 biodiesel.展开更多
BACKGROUND： Astrocytes are considered to provide nutritional support in the central nervous system. However, recent studies have confirmed that astrocytes also play an important role in chronic pain. OBJECTIVE： To i...BACKGROUND： Astrocytes are considered to provide nutritional support in the central nervous system. However, recent studies have confirmed that astrocytes also play an important role in chronic pain. OBJECTIVE： To investigate the effects of intrathecal injection of fluorocitrate, minocycline or both on astrocyte activation and proliferation in the spinal dorsal horn of compressed dorsal root ganglion in rats. DESIGN, TIME AND SETTING： The neurology randomized controlled animal study was performed at the Jiangsu Institute of Anesthesia Medicine, from September 2006 to April 2007. MATERIALS： A total of 96 male Sprague Dawley rats, aged 6-8 weeks, were selected for this study. Following intrathecal catheterization, 80 rats underwent steel bar insertion into the L4-5 intervertebral foramina to make a stable compression on the L4-5 posterior root ganglion. Thus rat models of ganglion compression were established. Minocycline and fluorocitrate were purchased from Sigma, USA. METHODS： A total of 96 rats were randomly and equally divided into six groups. Rat L4, L5 transverse process and intervertebral foramina were exposed in the sham operation group, but without steel bar insertion. The model group did not receive any manipulations. Rats in the phosphate buffered saline （PBS） group were intrathecally injected with 0.01 mmol/L PBS （20 μL）. Rats in the fluorocitrate group were subjected to 1 μmol/L fluorocitrate （20 μL）. Rats in the minocycline group were intrathecally injected with 5 g/L minocycline （20 μL）. Rats in the minocycline and fluorocitrate group received a mixture （20 μL） of 5 g/L minocycline and 1 μmol/L fluorocitrate. Following model establishment, drugs were administered once a day. MAIN OUTCOME MEASURES： At 7 and 14 days following model induction, glial fibrillary acidic protein expression in the spinal dorsal horn was measured by immunofluorescence microscopy. Six sections with significant glial fibrillary acidic protein -positive expression were obtained to count astrocytes under an inverted microscope. RESULTS： No significant differences in astrocyte count were detected between the fluorocitrate and model groups. Cell bodies were small with a few processes in the fluorocitrate group, compared with the model group. The astrocyte count decreased significantly in the minocycline group and the minocycline and fluorocitrate group compared with the sham operation, model, PBS and fluorocitrate groups （P 〈 0.01）. The decrease in astrocyte count was mainly found in layers Ⅲ–Ⅳ of the spinal dorsal horn. Cell body volume was smaller and process numbers were fewer in the minocycline group and the minocycline and fluorocitrate group, compared with the model and PBS groups. CONCLUSION： Fluorocitrate can inhibit astrocyte activation, but does not affect astrocyte proliferation. However, minocycline can inhibit the activation and proliferation of astrocytes.展开更多
In order to study the effect of two-stage injection on two-stroke diesel engines, a well characterized research engine equipped with electronically controlled common rail system and scavenging system was constructed. ...In order to study the effect of two-stage injection on two-stroke diesel engines, a well characterized research engine equipped with electronically controlled common rail system and scavenging system was constructed. Through analysis of combustion and emissions, two-stage injection shows its advantages. Compared with the standard injection, it produces less emissions, while compared with single early injection, it expands engine operation range. Further experiments were carried out to study the influence of several injection control parameters on two-stage injection. The fuel in the first injection is used for forming homogeneous mixture. The fuel in the second injection keeps combustion, and it is the main source of smoke emissions. NO_x is formed in both combustion process caused by these two injections, and there is an optimum fuel allocation ration to produce minimum NO_x. The cylinder pressure decreases, and the combustion is depressed with the increasing of scavenging pressure. By optimizing the injection control parameters of two-stage injection, NO_x and smoke can be reduced beyond 30% simultaneously.展开更多
Gasoline compression ignition(GCI)has been considered as a promising combustion concept to yield ultralow NOX and soot emissions while maintaining high thermal efficiency.However,how to improve the low-load performanc...Gasoline compression ignition(GCI)has been considered as a promising combustion concept to yield ultralow NOX and soot emissions while maintaining high thermal efficiency.However,how to improve the low-load performance becomes an urgent issue to be solved.In this paper,a GCI engine model was built to investigate the effects of internal EGR(i-EGR)and pre-injection on in-cylinder temperature,spatial concentration of mixture and OH radical,combustion and emission characteristics,and the control strategy for improving the combustion performance was further explored.The results showed an obvious expansion of the zone with an equivalence ratio between 0.8∼1.2 is realized by higher pre-injection ratios,and the s decreases with the increase of pre-injection ratio,but increases with the increase of i-EGR ratio.The high overlap among the equivalentmixture zone,the hightemperature zone,and the OH radical-rich zone can be achieved by higher i-EGR ratio coupled with higher preinjection ratio.By increasing the pre-injection ratio,the combustion efficiency increases first and then decreases,also achieves the peak value with a pre-injection ratio of 60%and is unaffected by i-EGR.The emissions of CO,HC,NOX,and soot can also be reduced to low levels by the combination of higher i-EGR ratios and a pre-injection ratio of 60%.展开更多
This article experimentally studies the effects of air injection near the blade trailing edge on flow separation and losses in a highly loaded linear compressor cascade. Aerodynamic parameters of eight cascades with d...This article experimentally studies the effects of air injection near the blade trailing edge on flow separation and losses in a highly loaded linear compressor cascade. Aerodynamic parameters of eight cascades with different air injection slot configura- tions are measured by using a five-hole probe at the cascade outlets. Ink-trace flow visualization is performed to obtain the flow details around the air injection slots. The static pressure distribution is clarified with pressure taps on the endwalls. The...展开更多
BACKGROUND A total of 100 patients diagnosed with mixed hemorrhoids from October 2022 to September 2023 in our hospital were randomly divided into groups by dice rolling and compared with the efficacy of different tre...BACKGROUND A total of 100 patients diagnosed with mixed hemorrhoids from October 2022 to September 2023 in our hospital were randomly divided into groups by dice rolling and compared with the efficacy of different treatment options.AIM To analyze the clinical effect and prognosis of mixed hemorrhoids treated with polidocanol injection combined with automatic elastic thread ligation operation(RPH).METHODS A total of 100 patients with mixed hemorrhoids who visited our hospital from October 2022 to September 2023 were selected and randomly divided into the control group(n=50)and the treatment group(n=50)by rolling the dice.The procedure for prolapse and hemorrhoids(PPH)was adopted in the control group,while polidocanol foam injection+RPH was adopted in the treatment group.The therapeutic effects,operation time,wound healing time,hospital stay,pain situation(24 hours post-operative pain score,first defecation pain score),quality of life(QOL),incidence of complications(post-operative hemorrhage,edema,infection),incidence of anal stenosis 3 months post-operatively and recurrence rate 1 year post-operatively of the two groups were compared.RESULTS Compared with the control group,the total effective rate of treatment group was higher,and the difference was significant(P<0.05).The operation time/wound healing time/hospital stay in the treatment group were shorter than those in the control group(P<0.05).The pain scores at 24 hours after operation/first defecation pain score of the treatment group was significantly lower than those in the control group(P<0.05).After surgery,the QOL scores of the two groups decreased,with the treatment group having higher scores than that of the control group(P<0.05).Compared with the control group,the incidence of postoperative complications in the treatment group was lower,and the difference was significant(P<0.05);However,there was no significant difference in the incidence of postoperative bleeding between the two groups(P>0.05);There was no significant difference in the incidence of anal stenosis 3 months after operation and the recurrence rate 1 year after operation between the two groups(P>0.05).CONCLUSION For patients with mixed hemorrhoids,the therapeutic effect achieved by using polidocanol injection combined with RPH was better.The wounds of the patients healed faster,the postoperative pain was milder,QOL improved,and the incidence of complications was lower,and the short-term and long-term prognosis was good.展开更多
Parametric study of tip injection was implemented experimentally on a subsonic axial flow compressor to understand the underlying flow mechanisms of stability improvement of the compressor with discrete tip injection....Parametric study of tip injection was implemented experimentally on a subsonic axial flow compressor to understand the underlying flow mechanisms of stability improvement of the compressor with discrete tip injection.Injector throat height varied from 2 to 6 times the height of rotor tip clearance,and circumferential coverage percentage ranged from 8.3% to 25% of the annulus.Static pressure fluctuations over the rotor tip were measured with fast-response pressure transducers.Whole-passage time-accurate simulations were also carried out to help us understand the flow details.The combinations of tip injection with traditional casing treatments were experimentally studied to generate an engineering-acceptable method of compressor stall control.The results indicate that the maximum stability improvement is achieved when injectors are choked despite their different sizes.The effect of circumferential coverage percentage on compressor stability depends on the value of injector throat height for un-choked injectors,and vice versa.Tip blockage in the blade passage is greatly reduced by the choked injectors,which is the primary reason for stability enhancement.The accomplishment of blockage diminishment is maintained in the circumferential direction with the unsteady effect of tip injection,which manifests as a hysteresis between the recovery of tip blockage and the recovery of tip leakage vortex.The unsteady effect is primarily responsible for the effectiveness of tip injection with a partial circumferential coverage.Tip injection cannot enhance the stability of the rotor with axial slots significantly,but it can improve the stability of the rotor with circumferential grooves further.The combined structure of tip injection with circumferential grooves is an alternative for engineering application.展开更多
Hydrogen displays the potential to partially replace pulverized coal injection(PCI)in the blast furnace,and it can reduce CO_(2)emissions.In this paper,a three-dimensional mathematical model of hydrogen and pulverized...Hydrogen displays the potential to partially replace pulverized coal injection(PCI)in the blast furnace,and it can reduce CO_(2)emissions.In this paper,a three-dimensional mathematical model of hydrogen and pulverized coal co-injection in blast furnace tuyere was established through numerical simulation,and the effect of hydrogen injection and oxygen enrichment interaction on pulverized coal combustion and raceway smelting was investigated.The simulation results indicate that when the coal injection rate decreased from 36 to 30t/h and the hydrogen injection increased from 0 to 3600 m^(3)/h,the CO_(2)emissions decreased from 1860 to 1551 kg/t,which represents a16.6%reduction,and the pulverized coal burnout decreased from 70.1%to 63.7%.The heat released from hydrogen combustion can not only promote the volatilization of pulverized coal but also affect the combustion reaction between volatilization and oxygen,which resulted in a decrease in the temperature at the end of the raceway.Co-injection of hydrogen with PCI increased the wall temperature near the upper half part of the raceway and at the outlet of the tuyere,which required a high cooling efficiency to extend the service life of the blast furnace.The increase in oxygen level compensated for the decreased average temperature in the raceway due to hydrogen injection.The increase in the oxygen content by 3%while maintaining constant hydrogen and PCI injection rates increased the burnout and average raceway temperature by 4.2%and 43 K,respectively.The mole fraction of CO and H_(2) production increased by 0.04 and 0.02,respectively.Burnout can be improved through optimization of the particle size distribution of pulverized coal.展开更多
基金supported by the National Key R&D Program of China[Grant No.2023YFF0713600]the National Natural Science Foundation of China[Grant No.62275062]+3 种基金Project of Shandong Innovation and Startup Community of High-end Medical Apparatus and Instruments[Grant No.2023-SGTTXM-002 and 2024-SGTTXM-005]the Shandong Province Technology Innovation Guidance Plan(Central Leading Local Science and Technology Development Fund)[Grant No.YDZX2023115]the Taishan Scholar Special Funding Project of Shandong Provincethe Shandong Laboratory of Advanced Biomaterials and Medical Devices in Weihai[Grant No.ZL202402].
文摘Photoacoustic-computed tomography is a novel imaging technique that combines high absorption contrast and deep tissue penetration capability,enabling comprehensive three-dimensional imaging of biological targets.However,the increasing demand for higher resolution and real-time imaging results in significant data volume,limiting data storage,transmission and processing efficiency of system.Therefore,there is an urgent need for an effective method to compress the raw data without compromising image quality.This paper presents a photoacoustic-computed tomography 3D data compression method and system based on Wavelet-Transformer.This method is based on the cooperative compression framework that integrates wavelet hard coding with deep learning-based soft decoding.It combines the multiscale analysis capability of wavelet transforms with the global feature modeling advantage of Transformers,achieving high-quality data compression and reconstruction.Experimental results using k-wave simulation suggest that the proposed compression system has advantages under extreme compression conditions,achieving a raw data compression ratio of up to 1:40.Furthermore,three-dimensional data compression experiment using in vivo mouse demonstrated that the maximum peak signal-to-noise ratio(PSNR)and structural similarity index(SSIM)values of reconstructed images reached 38.60 and 0.9583,effectively overcoming detail loss and artifacts introduced by raw data compression.All the results suggest that the proposed system can significantly reduce storage requirements and hardware cost,enhancing computational efficiency and image quality.These advantages support the development of photoacoustic-computed tomography toward higher efficiency,real-time performance and intelligent functionality.
基金supported by the National Natural Science Foundation of China(Grant No.42277147)Ningbo Public Welfare Research Program(Grant No.2024S081)Ningbo Natural Science Foundation(Grant No.2024J186).
文摘Rock brittleness is a critical property in geotechnical and energy engineering,as it directly influences the prediction of rock failure and stability assessment.Although numerous methods have been developed to evaluate brittleness,many fail to comprehensively account for the impacts of microstructural changes,mineralogical characteristics,and stress conditions on energy evolution during failure.This study proposes a novel approach for brittleness evaluation based on the energy evolution throughout the post-peak failure process,integrating two micromechanical mechanisms:crack propagation and frictional sliding.A new brittleness index is defined as the ratio of generated surface energy to released elastic energy,providing a unified framework for assessing both Class I and Class II mechanical behaviors.The brittleness of cyan,white,and gray sandstones was investigated under various confining pressures and moisture conditions using X-ray diffraction(XRD),scanning electron microscopy(SEM),and conventional triaxial compression(CTC)tests.The results demonstrate that brittleness decreases with increasing confining pressure,due to suppressed crack propagation,and increases under saturated conditions,as moisture enhances crack propagation.By establishing connections between mineral composition,microstructural features,and stress-induced responses,the proposed method overcame limitations of previous approaches and offered a more precise tool for evaluating rock brittleness under diverse environmental scenarios.
基金supported by the National Natural Science Foundation of China(U2341288 and 12302492)。
文摘An in-depth understanding of the behaviours of solid propellants under low-velocity impact loads is crucial for enhancing their safety in applications such as aerospace propulsion.This study investigated the dynamic responses of single ammonium perchlorate(AP)/octogen(HMX)particles embedded in a hydroxyl-terminated polybutadiene(HTPB)binder under dynamic compression loading via real-time synchrotron-based X-ray phase contrast imaging and a modified split Hopkinson pressure bar(SHPB)system.The compression of the viscoelastic binder and subsequent dynamic fracturing of the AP/HMX particles were captured.During compression,transverse cracks developed within the AP particles,and their propagation led to particle fracturing,resulting in ductile fracturing.Unlike AP,HMX generated numerous short cracks within the internal and edge regions simultaneously,leading to fragmentation and brittle fracturing.Moreover,particle damage reduced the modulus of the sample,shifting its dynamic stress response from nonlinear elasticity to strain softening and further strain hardening as the binder exhibited plastic deformation.A compression simulation incorporating a real particle microscopic structure was established to study the mechanical response of the interface and particles.The simulation results agreed with the experimental observations.These results indicate that the shear stress at the HTPB-AP interface is greater than that at the HTPB-HMX interface,which is a factor influencing the differences in the mesoscale damage mechanisms of the particles.
基金supported by 2023 Higher Education Scientific Research Planning Project of China Society of Higher Education(No.23PG0408)2023 Philosophy and Social Science Research Programs in Jiangsu Province(No.2023SJSZ0993)+2 种基金Nantong Science and Technology Project(No.JC2023070)Key Project of Jiangsu Province Education Science 14th Five-Year Plan(Grant No.B-b/2024/02/41)the Open Fund of Advanced Cryptography and System Security Key Laboratory of Sichuan Province(Grant No.SKLACSS-202407).
文摘Large language models(LLMs)have revolutionized AI applications across diverse domains.However,their widespread deployment has introduced critical security vulnerabilities,particularly prompt injection attacks that manipulate model behavior through malicious instructions.Following Kitchenham’s guidelines,this systematic review synthesizes 128 peer-reviewed studies from 2022 to 2025 to provide a unified understanding of this rapidly evolving threat landscape.Our findings reveal a swift progression from simple direct injections to sophisticated multimodal attacks,achieving over 90%success rates against unprotected systems.In response,defense mechanisms show varying effectiveness:input preprocessing achieves 60%–80%detection rates and advanced architectural defenses demonstrate up to 95%protection against known patterns,though significant gaps persist against novel attack vectors.We identified 37 distinct defense approaches across three categories,but standardized evaluation frameworks remain limited.Our analysis attributes these vulnerabilities to fundamental LLM architectural limitations,such as the inability to distinguish instructions from data and attention mechanism vulnerabilities.This highlights critical research directions such as formal verification methods,standardized evaluation protocols,and architectural innovations for inherently secure LLM designs.
文摘Background:Penile augmentation through injectable substances is becoming increasingly common.A growing number of aesthetic clinics are developing penile enlargement procedures using various injectable materials.Although these procedures are now performed in more controlled and medically supervised environments,their long-term outcomes remain poorly understood.The promotion of such medical treatments contributes to an increasing interest among adult males in self-injection as a method to alleviate psychological distress associated with penile size concerns.At the same time,access to injectable substances through unofficial or unregulated sources has become increasingly easy.Tor our knowledge,we report the first documented case of self-injection with Garamycin®(gentamicin)cream,contributing to the literature on the often multidisciplinary management of penile enlargement injections,a field still lacking well-established guidelines.Case Description:This case report describes a young patient who self-injected Garamycin®into the penis for the purpose of enlargement.He presented to our urology department with worsening symptoms,including severe and poorly tolerated pain.His primary request was prompt relief of pain while preserving,as much as possible,the aesthetic appearance and functional integrity of his penis.This case required a multi-stage surgical approach to salvage the penis and preserve both its structural integrity and functional outcome.Conclusions:To our knowledge,this case report documents the first reported instance of Garamycin®injection performed for the purpose of penile enlargement.It provides insight into the clinical course of such penile cream injections,demonstrates that a two-stage scrotal flap can achieve both functional and aesthetic outcomes,and highlights the importance of comprehensive management particularly addressing the traumatic impact of penile deformity secondary to inflammation and/or infection,as well as the body dysmorphic concerns often associated with these cases.
基金supported by the National Natural Science Foundation of China(Grant No.52339001).
文摘To investigate the damage evolution caused by stress-driven and sub-critical crack propagation within the Beishan granite under multi-creep triaxial compressive conditions,the distributed optical fiber sensing and X-ray computed tomography were combined to obtain the strain distribution over the sample surface and internal fractures of the samples.The Gini and skewness(G-S)coefficients were used to quantify strain localization during tests,where the Gini coefficient reflects the degree of clustering of elements with high strain values,i.e.,strain localization/delocalization.The strain localization-induced asymmetry of data distribution is quantified by the skewness coefficient.A precursor to granite failure is defined by the rapid and simultaneous increase of the G-S coefficients,which are calculated from strain increment,giving an earlier warning of failure by about 8%peak stress than those from absolute strain values.Moreover,the process of damage accumulation due to stress-driven crack propagation in Beishan granite is different at various confining pressures as the stress exceeds the crack initiation stress.Concretely,strain localization is continuous until brittle failure at higher confining pressure,while both strain localization and delocalization occur at lower confining pressure.Despite the different stress conditions,a similar statistical characteristic of strain localization during the creep stage is observed.The Gini coefficient increases,and the skewness coefficient decreases slightly as the creep stress is below 95%peak stress.When the accelerated strain localization begins,the Gini and skewness coefficients increase rapidly and simultaneously.
文摘Objective:To explore the therapeutic effect of double-puncture tympanic membrane puncture and tympanic cavity drug injection in patients with acute secretory otitis media.Methods:A total of 84 patients with acute secretory otitis media admitted to our hospital from June 2024 to June 2025 were selected and randomly divided into two groups by drawing lots.The control group(42 cases)was treated with the traditional single-puncture tympanic membrane puncture and tympanic cavity drug injection method,while the observation group(42 cases)was treated with the double-puncture tympanic membrane puncture and tympanic cavity drug injection method.The therapeutic effects of the two groups were compared.Results:The overall treatment response rate,overall complication rate,time to symptom relief,and improvement in hearing threshold in the observation group were all superior to those in the control group,with statistically significant differences(P<0.05).Conclusion:For acute secretory otitis media,the treatment method of double-puncture tympanic membrane puncture and tympanic cavity drug injection demonstrates definite efficacy,significantly reducing the incidence of complications,accelerating symptom relief,and improving hearing function,making it worthy of promotion.
基金support from the National Natural Science Foundation of China(Grant Nos.52104207 and 52374214)the Shandong Provincial Youth Innovation Team Development Program for Higher Education Institutions(Grant No.2023KJ305).
文摘In the field of rock engineering,the influence of water is a dynamic process that exhibits varying effects over time and across different locations.To further understand how water influences the mechanical properties and acoustic emission(AE)behavior of rocks,this study conducted uniaxial compression experiments on sandstones with varying degrees of wetting under both natural conditions and water-chemical environments.In addition,the study combined AE equipment with digital image correlation(DIC)to monitor the entire failure process.Using the sliding window algorithm,the variation in the variance of AE characteristic parameters during the process of sandstone loading to failure is analyzed from the perspective of critical slowing down.This analysis enables the effective identification of the early warning signal before failure.The experimental findings suggest that an increase in wetting height results in a gradual decrease in peak stress,accompanied by a concomitant increase in the percentage of shear cracks.The characteristic parameters,including energy,amplitude,and ringing count,all exhibit critical slowing phenomena.The waveform of AE characteristic parameters of the same sample is similar,and the mutation time of the precursor signal is roughly the same.All signals appear in the irreversible plastic deformation stage of microcrack initiation.The integration of critical slowing down theory and the b-value early warning method facilitates a more comprehensive evaluation of the stability of rock mass,thereby significantly enhancing the efficiency and safety of disaster prevention measures.
基金partially supported by the Center for Advanced Systems Understanding(CASUS)financed by Germany’s Federal Ministry of Education and Research(BMBF)+2 种基金the Saxon State Government out of the State Budget approved by the Saxon State Parliamentfunding from the European Union’s Just Transition Fund(JTF)within the project Röntgenlaser-Optimierung der Laserfusion(ROLF),Contract No.5086999001co-financed by the Saxon State Government out of the State Budget approved by the Saxon State Parliament.
文摘We present the first systematic experimental validation of return-current-driven cylindrical implosion scaling in micrometer-sized Cu and Al wires irradiated by J-class femtosecond laser pulses.Employing XFEL-based imaging with sub-micrometer spatial and femtosecond temporal resolution,supported by hydrodynamic and particle-in-cell simulations,we reveal how return current density depends precisely on wire diameter,material properties,and incident laser energy.We identify deviations from simple theoretical predictions due to geometrically influenced electron escape dynamics.These results refine and confirm the scaling laws essential for predictive modeling in high-energy-density physics and inertial fusion research.
文摘In order to enhance the off-peak performance of gas turbine combined cycle(GTCC)units,a novel collaborative power generation system(CPG)was proposed.During off-peak operation periods,the remaining power of the GTCC was used to drive the adiabatic compressed air energy storage(ACAES),while the intake air of the GTCC was heated by the compression heat of theACAES.Based on a 67.3MW GTCC,under specific demand load distribution,a CPG system and a benchmark system(BS)were designed,both of which used 9.388% of the GTCC output power to drive the ACAES.The performance of the CPG and the BS without intake air heating was compared.The results show that the load rate of the GTCC in the CPG system during off-peak periods is significantly enhanced,and the average operating efficiency of the GTCC is increased by 1.19 percentage points.However,in the BS system,due to the single collaborativemethod of load shifting,the GTCC operative efficiency is almost increased by 1.00 percentage points under different ambient temperatures.In a roundtrip cycle at an ambient temperature of 288.15K,the systemefficiency of the CPG reaches 0.5010,which is 0.62 percentage points higher than the operative efficiency of 0.4948 in the standalone GTCC;while the system efficiency of the BS is slightly inferior to that of the standalone GTCC.The findings confirm the technical feasibility and performance improvement of the ACAES-GTCC collaborative power generation system.
基金the Global-Top Project,Development of Advanced Combustion Technology for Global Top Low Emission Vehicle(2016002070001)the Ministry of Environment(MOE)of Korea for financial support by the Center for Environmentally Friendly Vehicle(CEFV)
文摘Dual-fuel premixed charge compression ignition (DF-PCCI) combustion has been proven to be a viable alternative to conventional diesel combustion in heavy-duty compression ignition engines due to its low nitrogen oxides (NOx) and particulate matter (PM) emissions. When natural gas (NG) is applied to a DF-PCCI engine, its low reactivity reduces the maximum pressure rise rate under high loads. However, the NG–diesel DF-PCCI engine suffers from low combustion efficiency under low loads. In this study, an injection strategy of fuel supply (NG and diesel) in a DF-PCCI engine was investigated in order to reduce both the fuel consumption and hydrocarbon (HC) and carbon monoxide (CO) emissions under low load conditions. A variation in the NG substitution and diesel start of energizing (SOE) was found to effectively control the formation of the fuel–air mixture. A double injection strategy of diesel was implemented to adjust the local reactivity of the mixture. Retardation of the diesel pilot SOE and a low fraction of the diesel pilot injection quantity were favorable for reducing the combustion loss. The introduction of exhaust gas recirculation (EGR) improved the fuel economy and reduced the NOx and PM emissions below Euro VI regulations by retarding the combustion phasing. The combination of an NG substitution of 40%, the double injection strategy of diesel, and a moderate EGR rate effectively improved the combustion efficiency and indicated efficiency, and reduced the HC and CO emissions under low load conditions.
基金Supported by the National Natural Science Foundation of China(No.82070920)Major Clinical Research Projects of the Three-Year Action Plan for Promoting Clinical Skills and Clinical Innovation in Municipal Hospitals(No.SHDC2020CR1043B-010)。
文摘·AIM:To evaluate the efficacy and safety of full-thickness sutures combined with intracameral air injection(FTS-AI)versus pre-Descemet’s membrane sutures combined with intracameral air injection(PDS-AI)in the management of acute corneal hydrops in keratoconus.·METHODS:The research included 8 patients(8 eyes)suffering from acute corneal hydrops caused by keratoconus.Four patients were randomly assigned to FTS-AI.And the other four were randomly assigned to PDS-AI.Corneal oedema,visual acuity,corneal thickness were assessed during follow-up.·RESULTS:The demographics,preoperative duration of symptoms and severity of corneal hydrops between the two groups were not significantly different.The mean corneal oedema resolution time after FTS-AI and PDSAI were 11±1.15 and 15±1.41 d,respectively(P=0.005).The maximum corneal thickness of the scarred region decreased in both groups at one week postoperatively(P<0.05).No obvious difference was found in the mean maximal corneal thickness between the two groups postoperatively.The BCVA improved significantly after FTS-AI and PDS-AI at three months postoperatively.No obvious difference was found in the BCVA after FTS-AI and PDS-AI at three months postoperatively.·CONCLUSION:FTS-AI and PDS-AI are safe and effective therapies to accelerate the resolution of corneal oedema in acute corneal hydrops secondary to keratoconus.Despite faster resolution of corneal oedema in the FTS-AI group,we recommend PDS-AI to avoid potential endothelium cell damage.
文摘This article analyses numerically the simultaneous influence of the compression rate, fuel nature and the advanced injection of fuel on maximum cylinder pressure during the combustion phrase with the help of the Python Spyder calculation code. Indeed, several authors have shown that the combustion of biofuels which make it possible to compensate for fossil and exhaustible resources, presents a cylinder pressure higher by about 3.5% compared to that of conventional diesel D100. This increase in pressure can be reduced by the means of controlling parameters making it possible to preserve the life of the engine and also reduce nitrogen oxides (NOx) and particular matter (PM). This article has two objectives which are: putting in place a numerical tool for the evaluation and simulation of thermal engines and the influence of control parameters on cylinder pressure. The single zone 0D combustion model which considers only the physical phenomena and considers the mixed fuel as a perfect gas is used. The fuel used is the Neem biofuel produced by Doctor Merlin Ayissi of the University of Douala and the D100 diesel fuel. The results are obtained from three fuel injection angles of 20°, 13° and 10° before the TDC (Top Dead Centre) and three values of the engine compression rates of 15, 20 and 25. The delay in combustion is characteristic of the fuel used as illustrated by the cetane number. The results show that the cylinder pressure increases with increasing compression rate and a very high advanced injection. It also shows that the pressure is high when diesel D100 is used instead of D100 biodiesel.
基金the Social Development Science and Technology Plan Program of Jiangsu Province, No. B2004515
文摘BACKGROUND： Astrocytes are considered to provide nutritional support in the central nervous system. However, recent studies have confirmed that astrocytes also play an important role in chronic pain. OBJECTIVE： To investigate the effects of intrathecal injection of fluorocitrate, minocycline or both on astrocyte activation and proliferation in the spinal dorsal horn of compressed dorsal root ganglion in rats. DESIGN, TIME AND SETTING： The neurology randomized controlled animal study was performed at the Jiangsu Institute of Anesthesia Medicine, from September 2006 to April 2007. MATERIALS： A total of 96 male Sprague Dawley rats, aged 6-8 weeks, were selected for this study. Following intrathecal catheterization, 80 rats underwent steel bar insertion into the L4-5 intervertebral foramina to make a stable compression on the L4-5 posterior root ganglion. Thus rat models of ganglion compression were established. Minocycline and fluorocitrate were purchased from Sigma, USA. METHODS： A total of 96 rats were randomly and equally divided into six groups. Rat L4, L5 transverse process and intervertebral foramina were exposed in the sham operation group, but without steel bar insertion. The model group did not receive any manipulations. Rats in the phosphate buffered saline （PBS） group were intrathecally injected with 0.01 mmol/L PBS （20 μL）. Rats in the fluorocitrate group were subjected to 1 μmol/L fluorocitrate （20 μL）. Rats in the minocycline group were intrathecally injected with 5 g/L minocycline （20 μL）. Rats in the minocycline and fluorocitrate group received a mixture （20 μL） of 5 g/L minocycline and 1 μmol/L fluorocitrate. Following model establishment, drugs were administered once a day. MAIN OUTCOME MEASURES： At 7 and 14 days following model induction, glial fibrillary acidic protein expression in the spinal dorsal horn was measured by immunofluorescence microscopy. Six sections with significant glial fibrillary acidic protein -positive expression were obtained to count astrocytes under an inverted microscope. RESULTS： No significant differences in astrocyte count were detected between the fluorocitrate and model groups. Cell bodies were small with a few processes in the fluorocitrate group, compared with the model group. The astrocyte count decreased significantly in the minocycline group and the minocycline and fluorocitrate group compared with the sham operation, model, PBS and fluorocitrate groups （P 〈 0.01）. The decrease in astrocyte count was mainly found in layers Ⅲ–Ⅳ of the spinal dorsal horn. Cell body volume was smaller and process numbers were fewer in the minocycline group and the minocycline and fluorocitrate group, compared with the model and PBS groups. CONCLUSION： Fluorocitrate can inhibit astrocyte activation, but does not affect astrocyte proliferation. However, minocycline can inhibit the activation and proliferation of astrocytes.
基金The National Basic Research Program of China(973 Program)(No.2001CB209208)The National Science Foundation of China(No.50136040)
文摘In order to study the effect of two-stage injection on two-stroke diesel engines, a well characterized research engine equipped with electronically controlled common rail system and scavenging system was constructed. Through analysis of combustion and emissions, two-stage injection shows its advantages. Compared with the standard injection, it produces less emissions, while compared with single early injection, it expands engine operation range. Further experiments were carried out to study the influence of several injection control parameters on two-stage injection. The fuel in the first injection is used for forming homogeneous mixture. The fuel in the second injection keeps combustion, and it is the main source of smoke emissions. NO_x is formed in both combustion process caused by these two injections, and there is an optimum fuel allocation ration to produce minimum NO_x. The cylinder pressure decreases, and the combustion is depressed with the increasing of scavenging pressure. By optimizing the injection control parameters of two-stage injection, NO_x and smoke can be reduced beyond 30% simultaneously.
基金sponsored by the projects of National Natural Science Foundation of China (Grant Nos.51806127 and 52075307)Key Research and Development Program of Shandong Province (Grant No.2019GHZ016).
文摘Gasoline compression ignition(GCI)has been considered as a promising combustion concept to yield ultralow NOX and soot emissions while maintaining high thermal efficiency.However,how to improve the low-load performance becomes an urgent issue to be solved.In this paper,a GCI engine model was built to investigate the effects of internal EGR(i-EGR)and pre-injection on in-cylinder temperature,spatial concentration of mixture and OH radical,combustion and emission characteristics,and the control strategy for improving the combustion performance was further explored.The results showed an obvious expansion of the zone with an equivalence ratio between 0.8∼1.2 is realized by higher pre-injection ratios,and the s decreases with the increase of pre-injection ratio,but increases with the increase of i-EGR ratio.The high overlap among the equivalentmixture zone,the hightemperature zone,and the OH radical-rich zone can be achieved by higher i-EGR ratio coupled with higher preinjection ratio.By increasing the pre-injection ratio,the combustion efficiency increases first and then decreases,also achieves the peak value with a pre-injection ratio of 60%and is unaffected by i-EGR.The emissions of CO,HC,NOX,and soot can also be reduced to low levels by the combination of higher i-EGR ratios and a pre-injection ratio of 60%.
基金National Natural Science Foundation of China (50876023)Chinese Specialized Research Fund for the Doctoral Pro-gram of Higher Education (20060213007)National Basic Research Program of China (2007CB210100)
文摘This article experimentally studies the effects of air injection near the blade trailing edge on flow separation and losses in a highly loaded linear compressor cascade. Aerodynamic parameters of eight cascades with different air injection slot configura- tions are measured by using a five-hole probe at the cascade outlets. Ink-trace flow visualization is performed to obtain the flow details around the air injection slots. The static pressure distribution is clarified with pressure taps on the endwalls. The...
文摘BACKGROUND A total of 100 patients diagnosed with mixed hemorrhoids from October 2022 to September 2023 in our hospital were randomly divided into groups by dice rolling and compared with the efficacy of different treatment options.AIM To analyze the clinical effect and prognosis of mixed hemorrhoids treated with polidocanol injection combined with automatic elastic thread ligation operation(RPH).METHODS A total of 100 patients with mixed hemorrhoids who visited our hospital from October 2022 to September 2023 were selected and randomly divided into the control group(n=50)and the treatment group(n=50)by rolling the dice.The procedure for prolapse and hemorrhoids(PPH)was adopted in the control group,while polidocanol foam injection+RPH was adopted in the treatment group.The therapeutic effects,operation time,wound healing time,hospital stay,pain situation(24 hours post-operative pain score,first defecation pain score),quality of life(QOL),incidence of complications(post-operative hemorrhage,edema,infection),incidence of anal stenosis 3 months post-operatively and recurrence rate 1 year post-operatively of the two groups were compared.RESULTS Compared with the control group,the total effective rate of treatment group was higher,and the difference was significant(P<0.05).The operation time/wound healing time/hospital stay in the treatment group were shorter than those in the control group(P<0.05).The pain scores at 24 hours after operation/first defecation pain score of the treatment group was significantly lower than those in the control group(P<0.05).After surgery,the QOL scores of the two groups decreased,with the treatment group having higher scores than that of the control group(P<0.05).Compared with the control group,the incidence of postoperative complications in the treatment group was lower,and the difference was significant(P<0.05);However,there was no significant difference in the incidence of postoperative bleeding between the two groups(P>0.05);There was no significant difference in the incidence of anal stenosis 3 months after operation and the recurrence rate 1 year after operation between the two groups(P>0.05).CONCLUSION For patients with mixed hemorrhoids,the therapeutic effect achieved by using polidocanol injection combined with RPH was better.The wounds of the patients healed faster,the postoperative pain was milder,QOL improved,and the incidence of complications was lower,and the short-term and long-term prognosis was good.
基金the support of the National Natural Science Foundation of China(Nos.51576162 and51236006)The Doctorate Foundation of Northwestern Polytechnical University(No.CX201422)
文摘Parametric study of tip injection was implemented experimentally on a subsonic axial flow compressor to understand the underlying flow mechanisms of stability improvement of the compressor with discrete tip injection.Injector throat height varied from 2 to 6 times the height of rotor tip clearance,and circumferential coverage percentage ranged from 8.3% to 25% of the annulus.Static pressure fluctuations over the rotor tip were measured with fast-response pressure transducers.Whole-passage time-accurate simulations were also carried out to help us understand the flow details.The combinations of tip injection with traditional casing treatments were experimentally studied to generate an engineering-acceptable method of compressor stall control.The results indicate that the maximum stability improvement is achieved when injectors are choked despite their different sizes.The effect of circumferential coverage percentage on compressor stability depends on the value of injector throat height for un-choked injectors,and vice versa.Tip blockage in the blade passage is greatly reduced by the choked injectors,which is the primary reason for stability enhancement.The accomplishment of blockage diminishment is maintained in the circumferential direction with the unsteady effect of tip injection,which manifests as a hysteresis between the recovery of tip blockage and the recovery of tip leakage vortex.The unsteady effect is primarily responsible for the effectiveness of tip injection with a partial circumferential coverage.Tip injection cannot enhance the stability of the rotor with axial slots significantly,but it can improve the stability of the rotor with circumferential grooves further.The combined structure of tip injection with circumferential grooves is an alternative for engineering application.
基金financially supported by the National Natural Science Foundation of China(No.51904026)the Fundamental Research Funds for the Central Universities(No.06500108)。
文摘Hydrogen displays the potential to partially replace pulverized coal injection(PCI)in the blast furnace,and it can reduce CO_(2)emissions.In this paper,a three-dimensional mathematical model of hydrogen and pulverized coal co-injection in blast furnace tuyere was established through numerical simulation,and the effect of hydrogen injection and oxygen enrichment interaction on pulverized coal combustion and raceway smelting was investigated.The simulation results indicate that when the coal injection rate decreased from 36 to 30t/h and the hydrogen injection increased from 0 to 3600 m^(3)/h,the CO_(2)emissions decreased from 1860 to 1551 kg/t,which represents a16.6%reduction,and the pulverized coal burnout decreased from 70.1%to 63.7%.The heat released from hydrogen combustion can not only promote the volatilization of pulverized coal but also affect the combustion reaction between volatilization and oxygen,which resulted in a decrease in the temperature at the end of the raceway.Co-injection of hydrogen with PCI increased the wall temperature near the upper half part of the raceway and at the outlet of the tuyere,which required a high cooling efficiency to extend the service life of the blast furnace.The increase in oxygen level compensated for the decreased average temperature in the raceway due to hydrogen injection.The increase in the oxygen content by 3%while maintaining constant hydrogen and PCI injection rates increased the burnout and average raceway temperature by 4.2%and 43 K,respectively.The mole fraction of CO and H_(2) production increased by 0.04 and 0.02,respectively.Burnout can be improved through optimization of the particle size distribution of pulverized coal.
