Accurate identification and effective support of key blocks are crucial for ensuring the stability and safety of rock slopes.The number of structural planes and rock blocks were reduced in previous studies.This impair...Accurate identification and effective support of key blocks are crucial for ensuring the stability and safety of rock slopes.The number of structural planes and rock blocks were reduced in previous studies.This impairs the ability to characterize complex rock slopes accurately and inhibits the identification of key blocks.In this paper,a knowledge-data dually driven paradigm for accurate identification of key blocks in complex rock slopes is proposed.Our basic idea is to integrate key block theory into data-driven models based on finely characterizing structural features to identify key blocks in complex rock slopes accurately.The proposed novel paradigm consists of(1)representing rock slopes as graph-structured data based on complex systems theory,(2)identifying key nodes in the graph-structured data using graph deep learning,and(3)mapping the key nodes of graph-structured data to corresponding key blocks in the rock slope.Verification experiments and real-case applications are conducted by the proposed method.The verification results demonstrate excellent model performance,strong generalization capability,and effective classification results.Moreover,the real case application is conducted on the northern slope of the Yanqianshan Iron Mine.The results show that the proposed method can accurately identify key blocks in complex rock slopes,which can provide a decision-making basis and rational recommendations for effective support and instability prevention of rock slopes,thereby ensuring the stability of rock engineering and the safety of life and property.展开更多
Concrete pavement often experiences accelerated deterioration due to water and chemical ingress through micro-cracks and surface voids.Particularly,the ingress of aggressive agents into the concrete matrix results in ...Concrete pavement often experiences accelerated deterioration due to water and chemical ingress through micro-cracks and surface voids.Particularly,the ingress of aggressive agents into the concrete matrix results in irreversible changes and deterioration on its endurance.Numerous studies unveiled that hydrophobic surface protection could be an inexpensive and effective way of enhancing the durability of concrete.This research work aims to assess the feasibility of bio-cement posttreatment for facilitating hydrophobic surface protection,thus enhancing the performance and durability of concrete blocks.Enzyme induced carbonate precipitation(EICP)is one of the promising bio-cement methods.Concrete blocks casted in four different grades were subjected to EICP treatment with different treatment schemes and recipes of cementation media.The treated blocks were tested for water absorption,ultrasonic pulse velocity(UPV)measurements,unconfined compressive strength(UCS),thermal performance,and scanning electron microscopy(SEM).The results indicated that the concrete blocks subjected to EICP posttreatment showed over a 55%reduction in water absorption,a 15%higher UCS and a 6.7%higher UPV when compared with control blocks.The SEM analysis suggested that the EICP posttreatment could enhance the durability of concrete paving blocks by enabling a layer of calcite on the surface and by plugging the transport pore channels of the concrete.Although most of the posttreatment strategies investigated herein were found to be operative,a better response was seen in the posttreatment by spraying scheme with 0.5 mol/L cementation media(CM).With the successful demonstration,the EICP treatment prior to the use of concrete blocks can be recommended to the pavement construction industry.展开更多
The purpose of this paper is to identify the processes with the highest contribution to potential environmental impacts in the life cycle of the masonry of concrete blocks by evaluating their main emissions contributi...The purpose of this paper is to identify the processes with the highest contribution to potential environmental impacts in the life cycle of the masonry of concrete blocks by evaluating their main emissions contributing to impact categories and identifying hotspots for environmental improvements.The research is based on the Life Cycle Assessment(LCA)study of non-load-bearing masonry of concrete blocks performed by the authors.The processes those have demonstrated higher contribution to environmental impacts were identified in the Life Cycle Impact Assessment(LCIA)phase and a detailed analysis was carried out on the main substances derived from these processes.The highest potential impacts in the life cycle of the concrete blocks masonry can be attributed mainly to emissions coming from the production of Portland cement,which explains the peak of impact potential on the blocks production stage,but also the significant impact potential in the use of the blocks for masonry construction,due to the use of cement mortar.The results of this LCA study are part of a major research on the comparative analysis of different typologies of non-load-bearing external walls,which aims to contribute to the creation of a life cycle database of major building systems,to be used by the environmental certification systems of buildings.展开更多
The behavior of single-phase flow and conjugate heat transfer in micro-channel heat sinks(MCHS)subjected to auniform heat flux is investigated by means of numerical simulations.Various geometrical configurations areex...The behavior of single-phase flow and conjugate heat transfer in micro-channel heat sinks(MCHS)subjected to auniform heat flux is investigated by means of numerical simulations.Various geometrical configurations areexamined,particularly,the combinations of rectangular solid and perforated blocks,used to create a disturbancein the flow.The analysis focuses on several key aspects and related metrics,including the temperature distribution,the mean Fanning friction factor,the pressure drop,the Nusselt number,and the overall heat transfer coefficientacross a range of Reynolds numbers(80–870).It is shown that the introduction of such blocks significantlyenhances the heat transfer performances of the MCHS compared to the straight-through flow channel.Specifically,a case is found where the Nusselt number increases by 2.3 times relative to the reference case.The integrationof perforated blocks facilitates the generation of vorticity within the channel,promoting the mixing of coldand hot fluids.Notably,MCHS incorporating perforated rectangular blocks exhibit more pronounced heat transferbenefits at Reynolds numbers smaller than 400.展开更多
Real-time monitoring of wellbore stability during drilling is crucial for the early detection of instability and timely interventions.The cause and type of wellbore instability can be identified by analyzing the dropp...Real-time monitoring of wellbore stability during drilling is crucial for the early detection of instability and timely interventions.The cause and type of wellbore instability can be identified by analyzing the dropped blocks brought to the surface by the drilling fluid,enabling preventive measures to be taken.In this study,an image capture system with fully automated sorting and 3D scanning was developed to obtain the complete 3D point cloud data of dropping blocks.The raw data obtained were preprocessed using methods such as format conversion,down sampling,coordinate transformation,statistical filtering,and clustering.Feature extraction algorithms,including the principal component analysis bounding box method,triangular meshing method,triaxial projection method,local curvature method,and model segmentation projection method,were employed,which resulted in the extraction of 32 feature parameters from the point cloud data.An optimal machine learning algorithm was developed by training it with 10 machine learning algorithms and the block data collected in the field.The XGBoost algorithm was then used to optimize the feature parameters and improve the classification model.An intelligent,fully automated feature parameter extraction and classification system was developed and applied to classify the types of falling blocks in 12 sets of drilling field and laboratory experiments and to identify the causes of wellbore instability.An average accuracy of 93.9%was achieved.This system can thus enable the timely diagnosis and implementation of preventive and control measures for wellbore instability in the field.展开更多
Correction to:Nuclear Science and Techniques(2024)35:145 https://doi.org/10.1007/s41365-024-01517-y In this article the author’s name Wan-Bing He was incorrectly written as Wan-Bin He.The original article has been co...Correction to:Nuclear Science and Techniques(2024)35:145 https://doi.org/10.1007/s41365-024-01517-y In this article the author’s name Wan-Bing He was incorrectly written as Wan-Bin He.The original article has been corrected.展开更多
As electro-hydrostatic actuator(EHA)technology advances towards lightweight and integration,the demand for enhanced internal flow pathways in hydraulic valve blocks intensifies.However,owing to the constraints imposed...As electro-hydrostatic actuator(EHA)technology advances towards lightweight and integration,the demand for enhanced internal flow pathways in hydraulic valve blocks intensifies.However,owing to the constraints imposed by traditional manufacturing processes,conventional hydraulic integrated valve blocks fail to satisfy the demands of a more compact channel layout and lower energy dissipation.Notably,the subjectivity in the arrangement of internal passages results in a time-consuming and labor-intensive process.This study employed additive manufacturing technology and the ant colony algorithm and B-spline curves for the meticulous design of internal passages within an aviation EHA valve block.The layout environment for the valve block passages was established,and path optimization was achieved using the ant colony algorithm,complemented by smoothing using B-spline curves.Three-dimensional modeling was performed using SolidWorks software,revealing a 10.03%reduction in volume for the optimized passages compared with the original passages.Computational fluid dynamics(CFD)simulations were performed using Fluent software,demonstrating that the algorithmically optimized passages effectively prevented the occurrence of vortices at right-angled locations,exhibited superior flow characteristics,and concurrently reduced pressure losses by 34.09%-36.36%.The small discrepancy between the experimental and simulation results validated the efficacy of the ant colony algorithm and B-spline curves in optimizing the passage design,offering a viable solution for channel design in additive manufacturing.展开更多
In blockchain-based unmanned aerial vehicle(UAV)communication systems,the length of a block affects the performance of the blockchain.The transmission performance of blocks in the form of finite character segments is ...In blockchain-based unmanned aerial vehicle(UAV)communication systems,the length of a block affects the performance of the blockchain.The transmission performance of blocks in the form of finite character segments is also affected by the block length.Therefore,it is crucial to balance the transmission performance and blockchain performance of blockchain communication systems,especially in wireless environments involving UAVs.This paper investigates a secure transmission scheme for blocks in blockchain-based UAV communication systems to prevent the information contained in blocks from being completely eavesdropped during transmission.In our scheme,using a friendly jamming UAV to emit jamming signals diminishes the quality of the eavesdropping channel,thus enhancing the communication security performance of the source UAV.Under the constraints of maneuverability and transmission power of the UAV,the joint design of UAV trajectories,transmission power,and block length are proposed to maximize the average minimum secrecy rate(AMSR).Since the optimization problem is non-convex and difficult to solve directly,we first decompose the optimization problem into subproblems of trajectory optimization,transmission power optimization,and block length optimization.Then,based on firstorder approximation techniques,these subproblems are reformulated as convex optimization problems.Finally,we utilize an alternating iteration algorithm based on the successive convex approximation(SCA)technique to solve these subproblems iteratively.The simulation results demonstrate that our proposed scheme can achieve secure transmission for blocks while maintaining the performance of the blockchain.展开更多
Discovery of materials using“bottom-up”or“top-down”approach is of great interest in materials science.Layered materials consisting of two-dimensional(2D)building blocks provide a good platform to explore new mater...Discovery of materials using“bottom-up”or“top-down”approach is of great interest in materials science.Layered materials consisting of two-dimensional(2D)building blocks provide a good platform to explore new materials in this respect.In van der Waals(vdW)layered materials,these building blocks are charge neutral and can be isolated from their bulk phase(top-down),but usually grow on substrate.In ionic layered materials,they are charged and usually cannot exist independently but can serve as motifs to construct new materials(bottom-up).In this paper,we introduce our recently constructed databases for 2D material-substrate interface(2DMSI),and 2D charged building blocks.For 2DMSI database,we systematically build a workflow to predict appropriate substrates and their geometries at substrates,and construct the 2DMSI database.For the 2D charged building block database,1208 entries from bulk material database are identified.Information of crystal structure,valence state,source,dimension and so on is provided for each entry with a json format.We also show its application in designing and searching for new functional layered materials.The 2DMSI database,building block database,and designed layered materials are available in Science Data Bank at https://doi.org/10.57760/sciencedb.j00113.00188.展开更多
BACKGROUND Anterior cutaneous nerve entrapment syndrome(ACNES)is a condition mani-festing with pain caused by strangulation of the anterior cutaneous branch of the lower intercostal nerves.This case report aims to pro...BACKGROUND Anterior cutaneous nerve entrapment syndrome(ACNES)is a condition mani-festing with pain caused by strangulation of the anterior cutaneous branch of the lower intercostal nerves.This case report aims to provide new insight into the selection of peripheral nerve blocks for the ACNES treatment.CASE SUMMARY A 66-year-old woman manifested ACNES after a robot-assisted distal gastrec-tomy.An ultrasound-guided rectal sheath block was effective for pain triggered by the port scar.However,the sudden severe pain,which radiated laterally from the previous site,remained.A transversus abdominis plane block was performed for the remaining pain and effectively relieved it.CONCLUSION In this case,the trocar port was inserted between the rectus and transverse abdominis muscles.The intercostal nerves might have been entrapped on both sides of the rectus and transversus abdominis muscles.Hence,rectus sheath and transverse abdominis plane blocks were required to achieve complete pain relief.To the best of our knowledge,this is the first report on use of a combination of rectus sheath and transverse abdominis plane blocks for pain relief in ACNES.展开更多
The design and synthesis of high-nuclear polyoxometalates(POMs)utilizing secondary building blocks(SBB)is attractive and challenging.Herein,four new high-nuclear polyoxovanadates(POVs),{V_(20)S_(2)In_(42)P_(12)(CO_(2)...The design and synthesis of high-nuclear polyoxometalates(POMs)utilizing secondary building blocks(SBB)is attractive and challenging.Herein,four new high-nuclear polyoxovanadates(POVs),{V_(20)S_(2)In_(42)P_(12)(CO_(2))}(1),{V_(20)Mo_(2)In_(4)P_(12)(C_(2)O_(4))_(2)}(2),{V_(12)P_(6)SPb_(2)}(3)and{V_(12)P_(6)SCd_(2)}(4),were successfully synthesized under solvothermal conditions by incorporating transition metals into POVs.All the structures are constructed from the tetragonal{V_(5)(PhPO_(3))_(4)}SBB,wherein five{VO_(5)}square pyramids are interconnected by edge-sharing modes,and four phenylphosphonic acid ligands further coordinate with vanadium cations.Compounds 1 and 2 have similar structures in which two{V_(10)(PhPO_(3))_(6)(SO_(4))In_(2)}or{V_(10)(PhPO_(3))_(6)(MoO_(4))In_(2)}clusters are bridged by formate or oxalate ligands.While compounds 3 and 4 are constructed from{V_(12)(PhPO_(3))_(6)(SO_(4))}cluster doped with transition metals Pb or Cd.Notably,compound 4 demonstrated efficient catalytic activity for sulfide oxidation.展开更多
BACKGROUND Osteonecrosis or avascular necrosis(AVN)of the hip was one of the dreaded complications of coronavirus disease 2019(COVID-19),which emerged in patients who received steroid therapy.Corticosteroids have been...BACKGROUND Osteonecrosis or avascular necrosis(AVN)of the hip was one of the dreaded complications of coronavirus disease 2019(COVID-19),which emerged in patients who received steroid therapy.Corticosteroids have been a mainstay in the treatment protocol of COVID-19 patients.Popular corticosteroid drugs used in patients suffering from COVID-19 were intravenous(IV)or oral dexamethasone,methylprednisolone or hydrocortisone.The use of such high doses of corticost-eroids has shown very positive results and has been lifesaving in many cases.Still,long-term consequences were drug-induced diabetes,osteoporosis,Cushing syndrome,muscle wasting,peripheral fat mobilization,AVN,hirsutism,sleep disturbances and poor wound healing.A significant number of young patients were admitted for bilateral total hip replacements(THR)secondary to AVN following steroid use for COVID-19 treatment.AIM To assess the efficacy of bilateral pericapsular end nerve group(PENG)blocks in patients posted for bilateral THR post-steroid therapy after COVID-19 infection and assess the time taken to first ambulate after surgery.METHODS This prospective observational study was conducted between January 2023 and August 2023 at Care Hospitals,Hyderabad,India.Twenty young patients 30-35 years of age who underwent bilateral THR were studied after due consent over 8 months.All the patients received spinal anaesthesia for surgery and bilateral PENG blocks for postoperative analgesia.RESULTS The duration of surgery was 2.5 h on average.Seventeen out of twenty patients(85%)had a Visual Analog Score(VAS)of less than 2 and did not require any supplementation.One patient was removed from the study,as he required re-exploration.The remaining two patients had a VAS of more than 8 and received IV morphine post-operatively as a rescue analgesic drug.Fifteen out of seventeen patients(88.2%)could be mobilized 12 h after the procedure.CONCLUSION Osteonecrosis or AVN of the hip was one of the dreaded complications of COVID-19,which surfaced in patients who received steroid therapy requiring surgical intervention.Bilateral PENG block is an effective technique to provide post-operative analgesia resulting in early mobilization and enhanced recovery after surgery.展开更多
The use of soil as a construction material is limited due to climatic conditions such as rain and wind effects. The valorization of industrial and agricultural by-products in soil-material-based composites for constru...The use of soil as a construction material is limited due to climatic conditions such as rain and wind effects. The valorization of industrial and agricultural by-products in soil-material-based composites for construction materials is an alternative to producing eco-materials for building construction. This study evaluates the effect of Shea Butter residue (SBr) and hydrated lime (HL) as stabilizers on the performance of Compressed Earth Blocks (CEB). For the production of CEB specimens, firstly the dry mixtures were prepared using soil material and 5 wt% HL, 5% - 25% wt% SBr and secondly, the appropriate amount of water was thoroughly mixed with the dry mixtures using the result of the proctor compaction test. All the moistened mixtures were mechanically pressed into CEBs on mold size (29.5 cm × 14 cm × 9.5 cm), cured at ambient temperature in the lab for 0 - 45 days, and dried at 60˚C for 7 days before being tested. The results give for the accessible porosity, bulk density, maximum dry and wet compressive strength, the respective value 31.58%;1580 kg/cm2;3.26 MPa and 0.75 MPa for CEB stabilized with 5 wt% lime without SBr. Moreover, the abrasion coefficient (14.49 cm2/g), the mass lost (0.08%), the surface depth (3.25 mm/h), the eroded surface (9.12 cm2), the sorptivity (0.046 g/cm2·min1/2 the absorption by total immersion at 2 h and 24 h (4.06 and 11.94%) are best for the CEBs stabilized with 5/5 wt% HL/SSBr. However, the lower thermal properties were obtained with CEB stabilized with 25 wt% SSBr. We therefore observe the significant reaction between these industrial and agricultural by-products with the earth material, with effects particularly on the hydric, thermal and durability properties. The use of industrial and agricultural by-products such as lime and SBr at an appropriate rate of 5 wt% are suitable to improve CEBs performances.展开更多
On the description of the landscapes of historical blocks in China,this paper proposes the approaches to renovating the historical blocks,including their repairing and reconstruction. It aims at presenting suggestions...On the description of the landscapes of historical blocks in China,this paper proposes the approaches to renovating the historical blocks,including their repairing and reconstruction. It aims at presenting suggestions for the protection and development of historical blocks through analyzing the methods and procedures for repairing and rebuilding the infrastructures and green landscapes in the blocks.展开更多
The coefficients of friction and squeezing of the key blocks comer in the roof structure of underground coalface are key factors to roof structure stability quantitative analysis. In this paper, through the special t...The coefficients of friction and squeezing of the key blocks comer in the roof structure of underground coalface are key factors to roof structure stability quantitative analysis. In this paper, through the special test of three-type corner friction and squeez- ing of real rock specimens, and physical simulation test on the roof key blocks of roof structure as well as the finite element calcula- tion of the corner stress distribution and failure mechanism, the characteristics of friction and squeezing of the roof key blocks comer are revealed. It is found that the friction angle of the roof key blocks corner is the residual friction angle, and the frictional angle of the roof key blocks is 22-32° (average 27°), so the friction coefficient is determined as 0.5. It also found the squeezing strength is less than the uniaxial strength, and the squeezing coefficient of the roof blocks corner is determined as 0.4. Based on the results, the ground control theory can be updated from qualitative analysis to quantitative analysis.展开更多
BACKGROUND Coronavirus disease 2019(COVID-19)caused by the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has resulted in a worldwide health crisis since it first appeared.Numerous studies demonstrated the...BACKGROUND Coronavirus disease 2019(COVID-19)caused by the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has resulted in a worldwide health crisis since it first appeared.Numerous studies demonstrated the virus’s predilection to cardiomyocytes;however,the effects that COVID-19 has on the cardiac conduc-tion system still need to be fully understood.AIM To analyze the impact that COVID-19 has on the odds of major cardiovascular complications in patients with new onset heart blocks or bundle branch blocks(BBB).METHODS The 2020 National Inpatient Sample(NIS)database was used to identify patients admitted for COVID-19 pneumonia with and without high-degree atrioven-tricular blocks(HDAVB)and right or left BBB utilizing ICD-10 codes.The patients with pre-existing pacemakers,suggestive of a prior diagnosis of HDAVB or BBB,were excluded from the study.The primary outcome was inpatient mortality.Secondary outcomes included total hospital charges(THC),the length of hospital stay(LOS),and other major cardiac outcomes detailed in the Results section.Univariate and multivariate regression analyses were used to adjust for confounders with Stata version 17.RESULTS A total of 1058815 COVID-19 hospitalizations were identified within the 2020 NIS database,of which 3210(0.4%)and 17365(1.6%)patients were newly diagnosed with HDAVB and BBB,respectively.We observed a significantly higher odds of in-hospital mortality,cardiac arrest,cardiogenic shock,sepsis,arrythmias,and acute kidney injury in the COVID-19 and HDAVB group.There was no statistically significant difference in the odds of cerebral infarction or pulmonary embolism.Encounters with COVID-19 pneumonia and newly diagnosed BBB had a higher odds of arrythmias,acute kidney injury,sepsis,need for mechanical ventilation,and cardiogenic shock than those without BBB.However,unlike HDAVB,COVID-19 pneumonia and BBB had no significant impact on mortality compared to patients without BBB.CONCLUSION In conclusion,there is a significantly higher odds of inpatient mortality,cardiac arrest,cardiogenic shock,sepsis,acute kidney injury,supraventricular tachycardia,ventricular tachycardia,THC,and LOS in patients with COVID-19 pneumonia and HDAVB as compared to patients without HDAVB.Likewise,patients with COVID-19 pneumonia in the BBB group similarly have a higher odds of supraventricular tachycardia,atrial fibrillation,atrial flutter,ventricular tachycardia,acute kidney injury,sepsis,need for mechanical ventilation,and cardiogenic shock as compared to those without BBB.Therefore,it is essential for healthcare providers to be aware of the possible worse predicted outcomes that patients with new-onset HDAVB or BBB may experience following SARS-CoV-2 infection.展开更多
The demands for improved fuel economy,performance and emissions continue to pose challenges for engine designers and the materials they choose. This is particularly true for modern diesel engines,where the primary pat...The demands for improved fuel economy,performance and emissions continue to pose challenges for engine designers and the materials they choose. This is particularly true for modern diesel engines,where the primary path to achieving improved engine performance and emissions is to increase the Peak Firing Pressure in the combustion chamber. The resulting increase in thermal and mechanical loading has required a change from conventional grey cast iron to Compacted Graphite Iron (CGI) in order to satisfy durability requirements without increasing the size or the weight of the engines. With at least 75% higher tensile strength,45% higher stiffness and approximately double the fatigue strength of conventional grey cast iron,CGI satisfies durability requirements and also provides the dimensional stability required to meet emissions legislation throughout the life of the engine. Currently,there are no CGI diesel engines running on the roads in North America. This is set to change considerably as new commercial vehicle and pick-up SUV diesel engines are launched with CGI cylinder blocks in 2008 and 2009. These initial programs will provide over 2 million CGI diesel engines when ramped to mature volume,potentially accounting for 10%-15% of the North American passenger vehicle fleet within the next four years.展开更多
Optimization design of hydraulic manifold blocks (HMB) is studied as acomplex solid spatial layout problem. Based on comprehensive research into structure features anddesign rules of HMB, an optimal mathematical model...Optimization design of hydraulic manifold blocks (HMB) is studied as acomplex solid spatial layout problem. Based on comprehensive research into structure features anddesign rules of HMB, an optimal mathematical model for this problem is presented. Usinghuman-computer cooperative genetic algorithm (GA) and its hybrid optitation strategies, integratedlayout and connection design schemes of HMB can be automatically optimized. An example is given totestify it.展开更多
In order to decrease both computational complexity and coding time, an improved algorithm for the early detection of all-zero blocks （AZBs） in H. 264/AVC is proposed. The previous AZBs detection algorithms are revie...In order to decrease both computational complexity and coding time, an improved algorithm for the early detection of all-zero blocks （AZBs） in H. 264/AVC is proposed. The previous AZBs detection algorithms are reviewed. Three types of transformed frequency-domain coefficients, which are quantized to zeros, are analyzed. Based on the three types of frequencydomain scaling factors, the corresponding spatial coefficients are derived. Then the Schwarz inequality is applied to the derivation of the three thresholds based on spatial coefficients. Another threshold is set on the basis of the probability distribution of zero coefficients in a block. As a result, an adaptive AZBs detection algorithm is proposed based on the minimum of the former three thresholds and the threshold of zero blocks distribution. The simulation results show that, compared with the existing AZBs detection algorithms, the proposed algorithm achieves a 5% higher detection ratio in AZBs and 4% to 10% computation saving with only 0. 1 dB video quality degradation.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42277161,42230709).
文摘Accurate identification and effective support of key blocks are crucial for ensuring the stability and safety of rock slopes.The number of structural planes and rock blocks were reduced in previous studies.This impairs the ability to characterize complex rock slopes accurately and inhibits the identification of key blocks.In this paper,a knowledge-data dually driven paradigm for accurate identification of key blocks in complex rock slopes is proposed.Our basic idea is to integrate key block theory into data-driven models based on finely characterizing structural features to identify key blocks in complex rock slopes accurately.The proposed novel paradigm consists of(1)representing rock slopes as graph-structured data based on complex systems theory,(2)identifying key nodes in the graph-structured data using graph deep learning,and(3)mapping the key nodes of graph-structured data to corresponding key blocks in the rock slope.Verification experiments and real-case applications are conducted by the proposed method.The verification results demonstrate excellent model performance,strong generalization capability,and effective classification results.Moreover,the real case application is conducted on the northern slope of the Yanqianshan Iron Mine.The results show that the proposed method can accurately identify key blocks in complex rock slopes,which can provide a decision-making basis and rational recommendations for effective support and instability prevention of rock slopes,thereby ensuring the stability of rock engineering and the safety of life and property.
基金supported by the following two grants:(i)Japan Society for the Promotion of Science(JSPS)KAKENHI Grant Number JP22H01581(i)National Research Counsil(NRC)of Sri Lanka Investigator Driven Grant Number 22-041.
文摘Concrete pavement often experiences accelerated deterioration due to water and chemical ingress through micro-cracks and surface voids.Particularly,the ingress of aggressive agents into the concrete matrix results in irreversible changes and deterioration on its endurance.Numerous studies unveiled that hydrophobic surface protection could be an inexpensive and effective way of enhancing the durability of concrete.This research work aims to assess the feasibility of bio-cement posttreatment for facilitating hydrophobic surface protection,thus enhancing the performance and durability of concrete blocks.Enzyme induced carbonate precipitation(EICP)is one of the promising bio-cement methods.Concrete blocks casted in four different grades were subjected to EICP treatment with different treatment schemes and recipes of cementation media.The treated blocks were tested for water absorption,ultrasonic pulse velocity(UPV)measurements,unconfined compressive strength(UCS),thermal performance,and scanning electron microscopy(SEM).The results indicated that the concrete blocks subjected to EICP posttreatment showed over a 55%reduction in water absorption,a 15%higher UCS and a 6.7%higher UPV when compared with control blocks.The SEM analysis suggested that the EICP posttreatment could enhance the durability of concrete paving blocks by enabling a layer of calcite on the surface and by plugging the transport pore channels of the concrete.Although most of the posttreatment strategies investigated herein were found to be operative,a better response was seen in the posttreatment by spraying scheme with 0.5 mol/L cementation media(CM).With the successful demonstration,the EICP treatment prior to the use of concrete blocks can be recommended to the pavement construction industry.
文摘The purpose of this paper is to identify the processes with the highest contribution to potential environmental impacts in the life cycle of the masonry of concrete blocks by evaluating their main emissions contributing to impact categories and identifying hotspots for environmental improvements.The research is based on the Life Cycle Assessment(LCA)study of non-load-bearing masonry of concrete blocks performed by the authors.The processes those have demonstrated higher contribution to environmental impacts were identified in the Life Cycle Impact Assessment(LCIA)phase and a detailed analysis was carried out on the main substances derived from these processes.The highest potential impacts in the life cycle of the concrete blocks masonry can be attributed mainly to emissions coming from the production of Portland cement,which explains the peak of impact potential on the blocks production stage,but also the significant impact potential in the use of the blocks for masonry construction,due to the use of cement mortar.The results of this LCA study are part of a major research on the comparative analysis of different typologies of non-load-bearing external walls,which aims to contribute to the creation of a life cycle database of major building systems,to be used by the environmental certification systems of buildings.
基金funded by the Project of the Hubei Provincial Department of Science and Technology(Grant No.2022CFB957)the Project of Hubei Engineering University of Teaching Research(Grant No.JY2024032)+1 种基金Ministry of Education University-Industry Cooperation Collaborative Education Project(Grant No.220903584161245)College Students’Innovation and Entrepreneurship Training Program(Grant Nos.DC2024031,DC2024032).
文摘The behavior of single-phase flow and conjugate heat transfer in micro-channel heat sinks(MCHS)subjected to auniform heat flux is investigated by means of numerical simulations.Various geometrical configurations areexamined,particularly,the combinations of rectangular solid and perforated blocks,used to create a disturbancein the flow.The analysis focuses on several key aspects and related metrics,including the temperature distribution,the mean Fanning friction factor,the pressure drop,the Nusselt number,and the overall heat transfer coefficientacross a range of Reynolds numbers(80–870).It is shown that the introduction of such blocks significantlyenhances the heat transfer performances of the MCHS compared to the straight-through flow channel.Specifically,a case is found where the Nusselt number increases by 2.3 times relative to the reference case.The integrationof perforated blocks facilitates the generation of vorticity within the channel,promoting the mixing of coldand hot fluids.Notably,MCHS incorporating perforated rectangular blocks exhibit more pronounced heat transferbenefits at Reynolds numbers smaller than 400.
基金supported by the Scientific research and technology development projects of CNPC“Research on Key Technologies and Equipment for Drilling and Completion of 10000-m Ultra-deep Oil and Gas Resources”(No.2022ZG06)“Development of a Complete Set of 70 MPa Intelligent Managed Pressure Drilling Equipment”(No.2024ZG35).
文摘Real-time monitoring of wellbore stability during drilling is crucial for the early detection of instability and timely interventions.The cause and type of wellbore instability can be identified by analyzing the dropped blocks brought to the surface by the drilling fluid,enabling preventive measures to be taken.In this study,an image capture system with fully automated sorting and 3D scanning was developed to obtain the complete 3D point cloud data of dropping blocks.The raw data obtained were preprocessed using methods such as format conversion,down sampling,coordinate transformation,statistical filtering,and clustering.Feature extraction algorithms,including the principal component analysis bounding box method,triangular meshing method,triaxial projection method,local curvature method,and model segmentation projection method,were employed,which resulted in the extraction of 32 feature parameters from the point cloud data.An optimal machine learning algorithm was developed by training it with 10 machine learning algorithms and the block data collected in the field.The XGBoost algorithm was then used to optimize the feature parameters and improve the classification model.An intelligent,fully automated feature parameter extraction and classification system was developed and applied to classify the types of falling blocks in 12 sets of drilling field and laboratory experiments and to identify the causes of wellbore instability.An average accuracy of 93.9%was achieved.This system can thus enable the timely diagnosis and implementation of preventive and control measures for wellbore instability in the field.
文摘Correction to:Nuclear Science and Techniques(2024)35:145 https://doi.org/10.1007/s41365-024-01517-y In this article the author’s name Wan-Bing He was incorrectly written as Wan-Bin He.The original article has been corrected.
基金Supported by National Natural Science Foundation of China(Grant No.51890881)。
文摘As electro-hydrostatic actuator(EHA)technology advances towards lightweight and integration,the demand for enhanced internal flow pathways in hydraulic valve blocks intensifies.However,owing to the constraints imposed by traditional manufacturing processes,conventional hydraulic integrated valve blocks fail to satisfy the demands of a more compact channel layout and lower energy dissipation.Notably,the subjectivity in the arrangement of internal passages results in a time-consuming and labor-intensive process.This study employed additive manufacturing technology and the ant colony algorithm and B-spline curves for the meticulous design of internal passages within an aviation EHA valve block.The layout environment for the valve block passages was established,and path optimization was achieved using the ant colony algorithm,complemented by smoothing using B-spline curves.Three-dimensional modeling was performed using SolidWorks software,revealing a 10.03%reduction in volume for the optimized passages compared with the original passages.Computational fluid dynamics(CFD)simulations were performed using Fluent software,demonstrating that the algorithmically optimized passages effectively prevented the occurrence of vortices at right-angled locations,exhibited superior flow characteristics,and concurrently reduced pressure losses by 34.09%-36.36%.The small discrepancy between the experimental and simulation results validated the efficacy of the ant colony algorithm and B-spline curves in optimizing the passage design,offering a viable solution for channel design in additive manufacturing.
基金supported in part by the National Key R&D Program of China under Grant 2022YFB3104503in part by the China Postdoctoral Science Foundation under Grant 2024M750199+1 种基金in part by the National Natural Science Foundation of China under Grants 62202054,62002022 and 62472251in part by the Fundamental Research Funds for the Central Universities under Grant BLX202360.
文摘In blockchain-based unmanned aerial vehicle(UAV)communication systems,the length of a block affects the performance of the blockchain.The transmission performance of blocks in the form of finite character segments is also affected by the block length.Therefore,it is crucial to balance the transmission performance and blockchain performance of blockchain communication systems,especially in wireless environments involving UAVs.This paper investigates a secure transmission scheme for blocks in blockchain-based UAV communication systems to prevent the information contained in blocks from being completely eavesdropped during transmission.In our scheme,using a friendly jamming UAV to emit jamming signals diminishes the quality of the eavesdropping channel,thus enhancing the communication security performance of the source UAV.Under the constraints of maneuverability and transmission power of the UAV,the joint design of UAV trajectories,transmission power,and block length are proposed to maximize the average minimum secrecy rate(AMSR).Since the optimization problem is non-convex and difficult to solve directly,we first decompose the optimization problem into subproblems of trajectory optimization,transmission power optimization,and block length optimization.Then,based on firstorder approximation techniques,these subproblems are reformulated as convex optimization problems.Finally,we utilize an alternating iteration algorithm based on the successive convex approximation(SCA)technique to solve these subproblems iteratively.The simulation results demonstrate that our proposed scheme can achieve secure transmission for blocks while maintaining the performance of the blockchain.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61888102,52272172,and 52102193)the Major Program of the National Natural Science Foundation of China(Grant No.92163206)+2 种基金the National Key Research and Development Program of China(Grant Nos.2021YFA1201501 and 2022YFA1204100)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB30000000)the Fundamental Research Funds for the Central Universities.
文摘Discovery of materials using“bottom-up”or“top-down”approach is of great interest in materials science.Layered materials consisting of two-dimensional(2D)building blocks provide a good platform to explore new materials in this respect.In van der Waals(vdW)layered materials,these building blocks are charge neutral and can be isolated from their bulk phase(top-down),but usually grow on substrate.In ionic layered materials,they are charged and usually cannot exist independently but can serve as motifs to construct new materials(bottom-up).In this paper,we introduce our recently constructed databases for 2D material-substrate interface(2DMSI),and 2D charged building blocks.For 2DMSI database,we systematically build a workflow to predict appropriate substrates and their geometries at substrates,and construct the 2DMSI database.For the 2D charged building block database,1208 entries from bulk material database are identified.Information of crystal structure,valence state,source,dimension and so on is provided for each entry with a json format.We also show its application in designing and searching for new functional layered materials.The 2DMSI database,building block database,and designed layered materials are available in Science Data Bank at https://doi.org/10.57760/sciencedb.j00113.00188.
文摘BACKGROUND Anterior cutaneous nerve entrapment syndrome(ACNES)is a condition mani-festing with pain caused by strangulation of the anterior cutaneous branch of the lower intercostal nerves.This case report aims to provide new insight into the selection of peripheral nerve blocks for the ACNES treatment.CASE SUMMARY A 66-year-old woman manifested ACNES after a robot-assisted distal gastrec-tomy.An ultrasound-guided rectal sheath block was effective for pain triggered by the port scar.However,the sudden severe pain,which radiated laterally from the previous site,remained.A transversus abdominis plane block was performed for the remaining pain and effectively relieved it.CONCLUSION In this case,the trocar port was inserted between the rectus and transverse abdominis muscles.The intercostal nerves might have been entrapped on both sides of the rectus and transversus abdominis muscles.Hence,rectus sheath and transverse abdominis plane blocks were required to achieve complete pain relief.To the best of our knowledge,this is the first report on use of a combination of rectus sheath and transverse abdominis plane blocks for pain relief in ACNES.
基金financially supported by National Natural Science Foundation of China(22371032 and 22271023)
文摘The design and synthesis of high-nuclear polyoxometalates(POMs)utilizing secondary building blocks(SBB)is attractive and challenging.Herein,four new high-nuclear polyoxovanadates(POVs),{V_(20)S_(2)In_(42)P_(12)(CO_(2))}(1),{V_(20)Mo_(2)In_(4)P_(12)(C_(2)O_(4))_(2)}(2),{V_(12)P_(6)SPb_(2)}(3)and{V_(12)P_(6)SCd_(2)}(4),were successfully synthesized under solvothermal conditions by incorporating transition metals into POVs.All the structures are constructed from the tetragonal{V_(5)(PhPO_(3))_(4)}SBB,wherein five{VO_(5)}square pyramids are interconnected by edge-sharing modes,and four phenylphosphonic acid ligands further coordinate with vanadium cations.Compounds 1 and 2 have similar structures in which two{V_(10)(PhPO_(3))_(6)(SO_(4))In_(2)}or{V_(10)(PhPO_(3))_(6)(MoO_(4))In_(2)}clusters are bridged by formate or oxalate ligands.While compounds 3 and 4 are constructed from{V_(12)(PhPO_(3))_(6)(SO_(4))}cluster doped with transition metals Pb or Cd.Notably,compound 4 demonstrated efficient catalytic activity for sulfide oxidation.
文摘BACKGROUND Osteonecrosis or avascular necrosis(AVN)of the hip was one of the dreaded complications of coronavirus disease 2019(COVID-19),which emerged in patients who received steroid therapy.Corticosteroids have been a mainstay in the treatment protocol of COVID-19 patients.Popular corticosteroid drugs used in patients suffering from COVID-19 were intravenous(IV)or oral dexamethasone,methylprednisolone or hydrocortisone.The use of such high doses of corticost-eroids has shown very positive results and has been lifesaving in many cases.Still,long-term consequences were drug-induced diabetes,osteoporosis,Cushing syndrome,muscle wasting,peripheral fat mobilization,AVN,hirsutism,sleep disturbances and poor wound healing.A significant number of young patients were admitted for bilateral total hip replacements(THR)secondary to AVN following steroid use for COVID-19 treatment.AIM To assess the efficacy of bilateral pericapsular end nerve group(PENG)blocks in patients posted for bilateral THR post-steroid therapy after COVID-19 infection and assess the time taken to first ambulate after surgery.METHODS This prospective observational study was conducted between January 2023 and August 2023 at Care Hospitals,Hyderabad,India.Twenty young patients 30-35 years of age who underwent bilateral THR were studied after due consent over 8 months.All the patients received spinal anaesthesia for surgery and bilateral PENG blocks for postoperative analgesia.RESULTS The duration of surgery was 2.5 h on average.Seventeen out of twenty patients(85%)had a Visual Analog Score(VAS)of less than 2 and did not require any supplementation.One patient was removed from the study,as he required re-exploration.The remaining two patients had a VAS of more than 8 and received IV morphine post-operatively as a rescue analgesic drug.Fifteen out of seventeen patients(88.2%)could be mobilized 12 h after the procedure.CONCLUSION Osteonecrosis or AVN of the hip was one of the dreaded complications of COVID-19,which surfaced in patients who received steroid therapy requiring surgical intervention.Bilateral PENG block is an effective technique to provide post-operative analgesia resulting in early mobilization and enhanced recovery after surgery.
文摘The use of soil as a construction material is limited due to climatic conditions such as rain and wind effects. The valorization of industrial and agricultural by-products in soil-material-based composites for construction materials is an alternative to producing eco-materials for building construction. This study evaluates the effect of Shea Butter residue (SBr) and hydrated lime (HL) as stabilizers on the performance of Compressed Earth Blocks (CEB). For the production of CEB specimens, firstly the dry mixtures were prepared using soil material and 5 wt% HL, 5% - 25% wt% SBr and secondly, the appropriate amount of water was thoroughly mixed with the dry mixtures using the result of the proctor compaction test. All the moistened mixtures were mechanically pressed into CEBs on mold size (29.5 cm × 14 cm × 9.5 cm), cured at ambient temperature in the lab for 0 - 45 days, and dried at 60˚C for 7 days before being tested. The results give for the accessible porosity, bulk density, maximum dry and wet compressive strength, the respective value 31.58%;1580 kg/cm2;3.26 MPa and 0.75 MPa for CEB stabilized with 5 wt% lime without SBr. Moreover, the abrasion coefficient (14.49 cm2/g), the mass lost (0.08%), the surface depth (3.25 mm/h), the eroded surface (9.12 cm2), the sorptivity (0.046 g/cm2·min1/2 the absorption by total immersion at 2 h and 24 h (4.06 and 11.94%) are best for the CEBs stabilized with 5/5 wt% HL/SSBr. However, the lower thermal properties were obtained with CEB stabilized with 25 wt% SSBr. We therefore observe the significant reaction between these industrial and agricultural by-products with the earth material, with effects particularly on the hydric, thermal and durability properties. The use of industrial and agricultural by-products such as lime and SBr at an appropriate rate of 5 wt% are suitable to improve CEBs performances.
基金Funded by the Scientific Support Project of the State Eleventh Five-Year Plan (2007BAQ01089)~~
文摘On the description of the landscapes of historical blocks in China,this paper proposes the approaches to renovating the historical blocks,including their repairing and reconstruction. It aims at presenting suggestions for the protection and development of historical blocks through analyzing the methods and procedures for repairing and rebuilding the infrastructures and green landscapes in the blocks.
基金This research was financially supported by the National Natural Science Foundation of China (No.50104009) and the Key Scienceand Technology Research Subject of the Ministry of Education of China (No.204183).
文摘The coefficients of friction and squeezing of the key blocks comer in the roof structure of underground coalface are key factors to roof structure stability quantitative analysis. In this paper, through the special test of three-type corner friction and squeez- ing of real rock specimens, and physical simulation test on the roof key blocks of roof structure as well as the finite element calcula- tion of the corner stress distribution and failure mechanism, the characteristics of friction and squeezing of the roof key blocks comer are revealed. It is found that the friction angle of the roof key blocks corner is the residual friction angle, and the frictional angle of the roof key blocks is 22-32° (average 27°), so the friction coefficient is determined as 0.5. It also found the squeezing strength is less than the uniaxial strength, and the squeezing coefficient of the roof blocks corner is determined as 0.4. Based on the results, the ground control theory can be updated from qualitative analysis to quantitative analysis.
文摘BACKGROUND Coronavirus disease 2019(COVID-19)caused by the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has resulted in a worldwide health crisis since it first appeared.Numerous studies demonstrated the virus’s predilection to cardiomyocytes;however,the effects that COVID-19 has on the cardiac conduc-tion system still need to be fully understood.AIM To analyze the impact that COVID-19 has on the odds of major cardiovascular complications in patients with new onset heart blocks or bundle branch blocks(BBB).METHODS The 2020 National Inpatient Sample(NIS)database was used to identify patients admitted for COVID-19 pneumonia with and without high-degree atrioven-tricular blocks(HDAVB)and right or left BBB utilizing ICD-10 codes.The patients with pre-existing pacemakers,suggestive of a prior diagnosis of HDAVB or BBB,were excluded from the study.The primary outcome was inpatient mortality.Secondary outcomes included total hospital charges(THC),the length of hospital stay(LOS),and other major cardiac outcomes detailed in the Results section.Univariate and multivariate regression analyses were used to adjust for confounders with Stata version 17.RESULTS A total of 1058815 COVID-19 hospitalizations were identified within the 2020 NIS database,of which 3210(0.4%)and 17365(1.6%)patients were newly diagnosed with HDAVB and BBB,respectively.We observed a significantly higher odds of in-hospital mortality,cardiac arrest,cardiogenic shock,sepsis,arrythmias,and acute kidney injury in the COVID-19 and HDAVB group.There was no statistically significant difference in the odds of cerebral infarction or pulmonary embolism.Encounters with COVID-19 pneumonia and newly diagnosed BBB had a higher odds of arrythmias,acute kidney injury,sepsis,need for mechanical ventilation,and cardiogenic shock than those without BBB.However,unlike HDAVB,COVID-19 pneumonia and BBB had no significant impact on mortality compared to patients without BBB.CONCLUSION In conclusion,there is a significantly higher odds of inpatient mortality,cardiac arrest,cardiogenic shock,sepsis,acute kidney injury,supraventricular tachycardia,ventricular tachycardia,THC,and LOS in patients with COVID-19 pneumonia and HDAVB as compared to patients without HDAVB.Likewise,patients with COVID-19 pneumonia in the BBB group similarly have a higher odds of supraventricular tachycardia,atrial fibrillation,atrial flutter,ventricular tachycardia,acute kidney injury,sepsis,need for mechanical ventilation,and cardiogenic shock as compared to those without BBB.Therefore,it is essential for healthcare providers to be aware of the possible worse predicted outcomes that patients with new-onset HDAVB or BBB may experience following SARS-CoV-2 infection.
文摘The demands for improved fuel economy,performance and emissions continue to pose challenges for engine designers and the materials they choose. This is particularly true for modern diesel engines,where the primary path to achieving improved engine performance and emissions is to increase the Peak Firing Pressure in the combustion chamber. The resulting increase in thermal and mechanical loading has required a change from conventional grey cast iron to Compacted Graphite Iron (CGI) in order to satisfy durability requirements without increasing the size or the weight of the engines. With at least 75% higher tensile strength,45% higher stiffness and approximately double the fatigue strength of conventional grey cast iron,CGI satisfies durability requirements and also provides the dimensional stability required to meet emissions legislation throughout the life of the engine. Currently,there are no CGI diesel engines running on the roads in North America. This is set to change considerably as new commercial vehicle and pick-up SUV diesel engines are launched with CGI cylinder blocks in 2008 and 2009. These initial programs will provide over 2 million CGI diesel engines when ramped to mature volume,potentially accounting for 10%-15% of the North American passenger vehicle fleet within the next four years.
基金This project is supported by Provincial ScienceTechnology Foundation of Liaoning (No. 20022132)
文摘Optimization design of hydraulic manifold blocks (HMB) is studied as acomplex solid spatial layout problem. Based on comprehensive research into structure features anddesign rules of HMB, an optimal mathematical model for this problem is presented. Usinghuman-computer cooperative genetic algorithm (GA) and its hybrid optitation strategies, integratedlayout and connection design schemes of HMB can be automatically optimized. An example is given totestify it.
基金The EU Seventh Framework Programme FP7-PEOPLE-IRSES( No. 247083)
文摘In order to decrease both computational complexity and coding time, an improved algorithm for the early detection of all-zero blocks （AZBs） in H. 264/AVC is proposed. The previous AZBs detection algorithms are reviewed. Three types of transformed frequency-domain coefficients, which are quantized to zeros, are analyzed. Based on the three types of frequencydomain scaling factors, the corresponding spatial coefficients are derived. Then the Schwarz inequality is applied to the derivation of the three thresholds based on spatial coefficients. Another threshold is set on the basis of the probability distribution of zero coefficients in a block. As a result, an adaptive AZBs detection algorithm is proposed based on the minimum of the former three thresholds and the threshold of zero blocks distribution. The simulation results show that, compared with the existing AZBs detection algorithms, the proposed algorithm achieves a 5% higher detection ratio in AZBs and 4% to 10% computation saving with only 0. 1 dB video quality degradation.
