AIM:To compare the efficacy of 3%diquafosol sodium(DQS)eye drops at different frequencies in dry eye(DE)after femtosecond laser-assisted in situ keratomileusis(FS-LASIK).METHODS:In this prospective study,DE patients a...AIM:To compare the efficacy of 3%diquafosol sodium(DQS)eye drops at different frequencies in dry eye(DE)after femtosecond laser-assisted in situ keratomileusis(FS-LASIK).METHODS:In this prospective study,DE patients after FS-LASIK were randomly divided into two groups.All patients were administered routine anti-inflammatory and anti-infective drugs after FS-LASIK.Additionally,both groups were treated with DQS,at frequencies of 4(DQS4 group)and 6(DQS6 group)times daily.Corneal fluorescein staining(CFS)score,non-invasive tear breakup time(NIBUT),tear meniscus height(TMH),lipid layer thickness(LLT),and incomplete blink rate(IBR)were assessed in patients preoperatively and at 1wk,1,and 3mo postoperatively.The Ocular Surface Disease Index(OSDI)questionnaire was also administered.RESULTS:Totally 119 patients(238 eyes)were randomly divided into the DQS4 group(60 individuals with 120 eyes)and DQS6 group(59 individuals with 118 eyes).From 1wk to 1mo after FS-LASIK,the CFS score in the DQS6 group decreased with statistical significance(P=0.014),while the DQS4 group showed an upward trend.Comparing with preoperative values,the NIBUT of both groups was significantly prolonged at various time points after FS-LASIK(P<0.05).Within 1mo post FS-LASIK,both groups had significantly higher OSDI scores compared with preoperative values(P<0.05).At postoperative 3mo,the DQS4 group recovered to a level similar to that before surgery(P>0.05),while the DQS6 group remained a little higher than preoperative values(P>0.05).The TMH levels in the DQS4 group increased significantly at 1wk postoperatively(P<0.05),while there was no statistically significant change in the TMH levels in the DQS6 group(P>0.05).There was no significant difference in IBR and LLT between the two groups within 1mo postoperatively.At postoperative 3mo,the LLT in the DQS4 group was significantly higher than that in the DQS6 group(P<0.05).CONCLUSION:Within 1mo post-FS-LASIK,applying DQS six times daily is superior to four daily applications in improving CFS score,and in increasing NIBUT meanwhile.After 1mo,applying DQS four times daily also effectively alleviate DE symptoms and improve DE signs.Therefore,we recommend DE patients using DQS eye drops 6 times daily within 1mo after FS-LASIK,and maintaining it 4 times daily until 3mo postoperatively.展开更多
The precision of landslide displacement prediction is crucial for effective landslide prevention and mitigation strategies.However,the role of surface monitoring frequency in influencing prediction accuracy has been l...The precision of landslide displacement prediction is crucial for effective landslide prevention and mitigation strategies.However,the role of surface monitoring frequency in influencing prediction accuracy has been largely neglected.This study examined the effect of varying monitoring frequencies on the accuracy of displacement predictions by using the Baijiabao landslide in the Three Gorges Reservoir Area(TGRA)as a case study.We collected surface automatic monitoring data at different intervals,ranging from daily to monthly.The Ensemble Empirical Mode Decomposition(EEMD)algorithm was utilized to dissect the accumulated displacements into periodic and trend components at each monitoring frequency.Polynomial fitting was applied to forecast the trend component while the periodic component was predicted with two state-of-the-art neural network models:Long Short-Term Memory(LSTM)and Gated Recurrent Unit(GRU).The predictions from these models were integrated to derive cumulative displacement forecasts,enabling a comparative analysis of prediction accuracy across different monitoring frequencies.The results demonstrate that the proposed models achieve high accuracy in landslide displacement forecasting,with optimal performance observed at moderate monitoring intervals.Intriguingly,the daily mean average error(MAE)decreases sharply with increasing monitoring frequency,reaching a plateau.These findings were corroborated by a parallel analysis of the Bazimen landslide,suggesting that moderate monitoring intervals of approximately 7 to 15 days are most conducive to achieving enhanced prediction accuracy compared to both daily and monthly intervals.展开更多
Using real fields instead of complex ones, it was recently claimed, that all fermions are made of pairs of coupled fields (strings) with an internal tension related to mutual attraction forces, related to Planck’s co...Using real fields instead of complex ones, it was recently claimed, that all fermions are made of pairs of coupled fields (strings) with an internal tension related to mutual attraction forces, related to Planck’s constant. The solution to Dirac equation gives four, real, 2-vectors solutions ψ1=(U1D1)ψ2=(U2D2)ψ3=(U3D3)ψ4=(U4D4)where (ψ1,ψ4) are coupled via linear combinations to yield spin-up and spin-down fermions. Likewise, (ψ2,ψ3) are coupled via linear combinations to represent spin-up and spin-down anti-fermions. Here, a deeper investigation of the free fermion internal frequency is discussed, hinting to an exchange interaction between the two components of which a fermion is made of. An upper limit estimate is given to the strength of this interaction.展开更多
OBJECTIVE:To observe the effect of different acupuncture frequencies on the abstinence rate which could be used as a reference for optimizing acupuncture cessation programs.METHODS:From July 2018 to June 2022,a total ...OBJECTIVE:To observe the effect of different acupuncture frequencies on the abstinence rate which could be used as a reference for optimizing acupuncture cessation programs.METHODS:From July 2018 to June 2022,a total of 220 smokers were recruited based on inclusion criteria and randomly divided into the high-frequency acupuncture group(HF group,n=110):5 times a week from the 1st to the 4th week,from weeks 5 to 8,three times a week and the low-frequency acupuncture group(LF group,n=110):3 times a week from the 1st to the 4th week,from weeks 5 to 8,twice a week,then treated for 8 weeks and followup at 1 month in Beijing.RESULTS:In total,162 subjects completed the whole study with a drop-out rate of 20.45%.The expiratory CO point abstinence rate was HF group 53/110(48.18%)vs LF group 41/110(37.27%)in Week 8(P=0.102)and HF group 46/110(41.82%)vs LF group 45/110(40.91%)in Week 12(P=0.891)and the HF acupuncture and LF acupuncture were nearly equal in the 8-week abstinence rate.In addition,both HF and LF acupuncture significantly reduced Fagerstr?m test for nicotine dependence scale(FTND)scores(P<0.05),Minnesota nicotine withdrawal scale(MNWS)scores(P<0.05),and Brief Questionnaire of Smoking Urges scale(QSU-Brief)scores(P<0.05),but HF acupuncture showed some superiority over LF acupuncture in relieving patients'smoking cravings(P<0.05).CONCLUSIONS:The study initially showed that both high-frequency acupuncture and low-frequency acupuncture treatment were safe and effective on smoking cessation for 8 weeks,but high-frequency acupuncture was advantageous in reducing smoking cravings.More accurate acupuncture frequency needs to be validated through larger clinical studies to optimize acupuncture smoking cessation programs.展开更多
Background:Anxiety and depression are prevalent among university students,calling for effec-tive non-pharmacological interventions.Tai Chi shows potential in reducing these symptoms,but research on its effects at diff...Background:Anxiety and depression are prevalent among university students,calling for effec-tive non-pharmacological interventions.Tai Chi shows potential in reducing these symptoms,but research on its effects at different frequencies in younger populations is limited.This study compared the impacts of high-(5 ses-sions/week),medium-(3 sessions/week),and low-frequency(2 sessions/week)24-form Tai Chi on college students’anxiety/depression,versus a control group.Methods:A randomized controlled trial(RCT)included 120 university students with mild-to-moderate anxiety/depression,randomly assigned to 4 groups(30 each).The 8-week intervention used the Self-Rating Anxiety Scale(SAS)and Self-Rating Depression Scale(SDS)for assessments at baseline,week 4,and week 8.Analyses included paired t-tests(within-group changes),one-way ANOVA(between-group differences),repeated measures ANOVA(RM-ANOVA,temporal changes),and Mixed Model for Repeated Measures(MMRM,longitudinal changes with missing data).Results:All intervention groups had significant SAS/SDS reductions:high-frequency group(SAS:20.4%,t=7.21,p<0.001;SDS:22.1%,t=6.92,p<0.001)>medium-frequency group(SAS:18.3%,t=5.06,p<0.001;SDS:19.8%,t=5.18,p<0.001)>low-frequency group(SAS:15.2%,t=4.09,p<0.001;SDS:17.4%,t=4.67,p<0.001).No changes were seen in the control group.The high-frequency group outperformed the low-frequency and control groups(p<0.05);RM-ANOVA and MMRM confirmed sustained,time-dependent effects,with the high-frequency group being optimal.Conclusion:24-form Tai Chi effectively reduces college students’anxiety/depression,with efficacy increasing with frequency(high>medium>low).The high-frequency protocol(5 sessions/week)is the most effective non-pharmacological intervention,and MMRM confirms its sustained efficacy.展开更多
As an evaluation index,the natural frequency has the advantages of easy acquisition and quantitative evaluation.In this paper,the natural frequency is used to evaluate the performance of external cable reinforced brid...As an evaluation index,the natural frequency has the advantages of easy acquisition and quantitative evaluation.In this paper,the natural frequency is used to evaluate the performance of external cable reinforced bridges.Numerical examples show that compared with the natural frequencies of first-order modes,the natural frequencies of higher-order modes are more sensitive and can reflect the damage situation and external cable reinforcement effect of T-beam bridges.For damaged bridges,as the damage to the T-beam increases,the natural frequency value of the bridge gradually decreases.When the degree of local damage to the beam reaches 60%,the amplitude of natural frequency change exceeds 10%for the first time.The natural frequencies of the firstorder vibration mode and higher-order vibration mode can be selected as indexes for different degrees of the damaged T-beam bridges.For damaged bridges reinforced with external cables,the traditional natural frequency of the first-order vibration mode cannot be used as the index,which is insensitive to changes in prestress of the external cable.Some natural frequencies of higher-order vibration modes can be selected as indexes,which can reflect the reinforcement effect of externally prestressed damaged T-beam bridges,and its numerical value increases with the increase of external prestressed cable force.展开更多
Acoustofluidics is a term describing the class of phenomena in which mechanical or acoustic vibrations induce a deformation or a flow in a fluid.Many deficiencies in our understanding of these phenomena remain to be a...Acoustofluidics is a term describing the class of phenomena in which mechanical or acoustic vibrations induce a deformation or a flow in a fluid.Many deficiencies in our understanding of these phenomena remain to be addressed,with respect to the fundamental theoretical framework as well as in numerous applications.In this regard,the frequency of external forcing is a key parameter.Owing to the low cost,substantial magnitude,and versatility associated with acoustofluidic phenomena at audible frequencies,studies of these phenomena in the audible range have emerged with increasing amount in recent years and have attracted considerable attention.However,compared with studies focusing on the ultrasonic frequency domain,critical features and information specific to audible acoustofluidics remain dispersed across many independent publications,and a systematic integration of the literature on this topic is necessary.Accordingly,this review summarizes the basic theory and methods for generating vibrations in the audible range,presents various applications thereof in biology,chemistry,and other fields,and provides a high-level overview of the current status of the topic to motivate developing interesting proposals for further research in this field of study.展开更多
With the gradual development and modernization of satellite navigation systems,using observation information from multi-GNss has become one of the hot-spot issues in recent years.Multi-system loose combinations form d...With the gradual development and modernization of satellite navigation systems,using observation information from multi-GNss has become one of the hot-spot issues in recent years.Multi-system loose combinations form double-difference observation equations within their respective systems,and the positioning effect is improved.However,the interchangeability and compatible interoperability between global navigation satellite systems(GNSS)cannot be truly realized.At the same time,when the number of visible satellites decreases abruptly,the positioning performance deteriorates sharply.This paper focuses on the GNsS multi-system tight combination relative positioning technique,gives a mathe-matical model of multi-system tight combination relative positioning considering differential inter-system bias(DISB),and analyzes the time-varying characteristics of DISB at overlapping and non-overlapping frequencies among GPS/Galileo,GPS/BDS,and GPS/QZSS in terms of receiver brand,tem-perature,and receiver restart.The GNsS tight combination relative positioning performance is verified by static data from Curtin University and dynamic data measured at Taiyuan University of Technology.The results show that compared with loose combination,the ambiguity-fixed rate increases from 62.18%to 97.60%for static data and from 74.97%to 99.53%for dynamic data when the elevation mask angle is 50°,resulting in a significant improvement in positioning performance.展开更多
In the cascaded H-bridge inverter(CHBI)with supercapacitor and dc-dc stage,inherent second-order harmonic power flows through each submodule(SM),causing fluctuations in both the dc-link voltage and the dc-dc current.T...In the cascaded H-bridge inverter(CHBI)with supercapacitor and dc-dc stage,inherent second-order harmonic power flows through each submodule(SM),causing fluctuations in both the dc-link voltage and the dc-dc current.There exist limitations in handling these fluctuations at variable output frequencies when employing proportional-integral(PI)control to the dc-dc stage.This paper aims to coordinately control these second-order harmonic voltage and current fluctuations in the CHBI.The presented method configures a specific second-order harmonic voltage reference,equipped with a maximum voltage fluctuation constraint and a suitable phase,for the dc-dc stage.A PI-resonant controller is used to track the configured reference.This allows for regulating the second-order harmonic fluctuation in the average dc-link voltage among the SMs within a certain value.Importantly,the second-order harmonic fluctuation in the dc-dc current can also be reduced.Simulation and experimental results demonstrate the effectiveness of the presented method.展开更多
This paper deals with wave propagation and power coupling in blue-core helicon plasma driven by various antennas and frequencies.It is found that compared to non-blue-core mode,for blue-core mode,the wave can propagat...This paper deals with wave propagation and power coupling in blue-core helicon plasma driven by various antennas and frequencies.It is found that compared to non-blue-core mode,for blue-core mode,the wave can propagate in the core region,and it decays sharply outside the core.The power absorption is lower and steeper in radius for blue-core mode.Regarding the effects of antenna geometry for blue-core mode,it shows that half helix antenna yields the strongest wave field and power absorption,while loop antenna yields the lowest.Moreover,near axis,for antennas with m=+1,the wave field increases with axial distance.In the core region,the wave number approaches to a saturation value at much lower frequency for non-blue-core mode compared to blue-core mode.The total loading resistance is much lower for blue-core mode.These findings are valuable to understanding the physics of blue-core helicon discharge and optimizing the experimental performance of blue-core helicon plasma sources for applications such as space propulsion and material treatment.展开更多
The bipolar ionic liquid thruster employs ionic liquid as a propellant to discharge positively and negatively charged high-energy particles under an alternating current(AC)power source,effectively suppressing electroc...The bipolar ionic liquid thruster employs ionic liquid as a propellant to discharge positively and negatively charged high-energy particles under an alternating current(AC)power source,effectively suppressing electrochemical reaction and ensuring charge neutrality.Determining an optimal AC supply power source frequency is critical for sustained stable thruster operation.This study focuses on the emission characteristics of the ionic liquid thruster under varied AC conditions.The AC power supply was set within the frequency range of 0.5-64 Hz,with eight specific frequency conditions selected for experimentation.The experimental results indicate that the thruster operates steadily within a voltage range of±1470 to±1920 V,with corresponding positive polarity current ranging from 0.41 to 4.91μA and negative polarity current ranging from−0.49 to−4.10μA.During voltage polarity switching,an emission delay occurs,manifested as a prominent peak signal caused by circuit capacitance characteristics and a minor peak signal resulting from liquid droplets.Extended emission test was conducted at 16 Hz,demonstrating approximately 1 h and 50 min of consistent emission before intermittent discharge.These findings underscore the favorable impact of AC conditions within the 8-16 Hz range on the self-neutralization capability of the ionic liquid thruster.展开更多
The boundary element method(BEM)is a popular method for solving acoustic wave propagation problems,especially those in exterior domains,owing to its ease in handling radiation conditions at infinity.However,BEM models...The boundary element method(BEM)is a popular method for solving acoustic wave propagation problems,especially those in exterior domains,owing to its ease in handling radiation conditions at infinity.However,BEM models must meet the requirement of 6–10 elements per wavelength,using the conventional constant,linear,or quadratic elements.Therefore,a large storage size of memory and long solution time are often needed in solving higher-frequency problems.In this work,we propose two new types of enriched elements based on conventional constant boundary elements to improve the computational efficiency of the 2D acoustic BEM.The first one uses a plane wave expansion,which can be used to model scattering problems.The second one uses a special plane wave expansion,which can be used tomodel radiation problems.Five examples are investigated to showthe advantages of the enriched elements.Compared with the conventional constant elements,the new enriched elements can deliver results with the same accuracy and in less computational time.This improvement in the computational efficiency is more evident at higher frequencies(with the nondimensional wave numbers exceeding 100).The paper concludes with the potential of our proposed enriched elements and plans for their further improvement.展开更多
Objective:Electroacupuncture(EA)is an alternative treatment option for pain.Different frequencies of EA have different painrelieving effects;however,the central mechanism is still not well understood.Methods:The Fos2A...Objective:Electroacupuncture(EA)is an alternative treatment option for pain.Different frequencies of EA have different painrelieving effects;however,the central mechanism is still not well understood.Methods:The Fos2A-iCreER(TRAP):Ai9 mice were divided into three groups(sham,2 Hz,and 100 Hz).The mice were intraperitoneally injected with 4-hydroxytamoxifen(4-OHT)immediately after EA at Zusanli(ST36)for 30 min to record the activated neurons.One week later,the mice were sacrificed,and the number of TRAP-treated neurons activated by EA in the thalamus,amygdala,cortex,and hypothalamus was determined.Results:In the cortex,2 Hz EA activated more TRAP-treated neurons than 100 Hz EA did in the cingulate cortex area 1(Cg1)and primary somatosensory cortex(S1),and 2 and 100 Hz EAs did not differ from sham EA.TRAP-treated neurons activated by 2 Hz EA were upregulated in the insular cortex(IC)and secondary somatosensory cortex(S2)compared with those activated by 100 Hz and sham EA.In the thalamus,the number of TRAP-treated neurons activated by 2 Hz EA was elevated in the paraventricular thalamic nucleus(PV)compared with those activated by sham EA.In the ventrolateral thalamic nucleus(VL),the number of TRAPtreated neurons activated by 2 Hz EA was significantly upregulated compared with those activated by 100 Hz EA,and sham EA showed no difference compared with 2 or 100 Hz EA.TRAP-treated neurons were more frequently activated in the ventral posterolateral thalamic nucleus(VPL)by 2 Hz EA than by 100 Hz or sham EA.Conclusions:Low-frequency EA ST36 effectively activates neurons in the Cg1,S1,S2,IC,VPL,PV,and VL.The enhanced excitability of the aforementioned nuclei induced by low-frequency EA may be related to its superior efficacy in the treatment of neuropathological pain.展开更多
Recently,abacafibers have become the focus of specialized research due to their intriguing characteristics,with their outstanding mechanical properties being a particularly notable.In the conducted study,the abacafibers...Recently,abacafibers have become the focus of specialized research due to their intriguing characteristics,with their outstanding mechanical properties being a particularly notable.In the conducted study,the abacafibers underwent a preliminary treatment process involving an alkaline solution,which was composed of 0.5%sodium hydroxide(NaOH)and 50%acetic acid(CH3COOH).This process entailed immersing eachfiber in the solution for a period of one hour.This treatment led to a 52.36%reduction in lignin content compared to the levels before treatment,resulting in a dramatic decrease in the full width at half maximum(FWHM)in the XRD spectra from 1.13 to 0.13.This change indicates that thefibers became more crystalline following the treatment.The abacafibers were also characterized using BET(Brunauer Emmett Teller)measurements,which revealed that the aver-age pore length ranged from 33–49 nm and the surface area was between 13–28 m^(2)·g^(-1).The morphology of the abacafiber after alkali an hydrolisis treatment(AFAH)appeared rougher and more uniform.DMA measurements revealed a significant rise in the storage modulus of the singlefiber post-treatment,with dependencies on both frequency and temperature.AFAH exhibited an optimal absorption coefficient ofα=0.9 for frequencies above 2500 Hz.The combined effect of alkalization and hydrolyzation treatments,while resulting in an enhancement in the mechanical properties of thefibers,also reduced high-intensity noise produced by sources such as machin-ery,aircraft takeoffs and landings,etc.,across a broader working frequency range.展开更多
Mitigating low-frequency noise poses a significant challenge for acoustic engineers,due to their long wavelength,with conventional porous sound absorbers showing limitations in attenuating such noise.An effective stra...Mitigating low-frequency noise poses a significant challenge for acoustic engineers,due to their long wavelength,with conventional porous sound absorbers showing limitations in attenuating such noise.An effective strategy involves combining porous materials with micro-perforated plates(MPP)to address this issue.Given the significant impact of structural variables like panel thickness,hole diameter,and air gap on the acoustic characteristics of MPP,achieving the optimal condition demands numerous sample iterations.The impedance tube’s considerable expense for sound absorption measurement and the substantial cost involved in fabricating each sample using a 3D printer underscore the advantage of utilizing simulation methods to attain the optimal state.This study focuses on optimizing low-frequency enhancement by investigating key parameters.Using the Finite Element Numerical Method(FEM)in COMSOL software,a composite panel was constructed comprising date palm fiber layers,an intervening air layer,and MPP.The study explored the arrangement of these layers and the impact of parameters like hole diameter,plate thickness,and perforation ratio on acoustic behavior.The selected optimal parameter at each stage was consistently maintained for subsequent steps.Results revealed that layer arrangement significantly influenced acoustic characteristics.Placing the MPP layer before the porous material yielded superior low-frequency performance.Optimizing low-frequency behavior involved reducing hole diameter and perforation ratio while increasing plate thickness.Elevating the porous material’s thickness relative to the air layer behind the MPP enhanced absorption peak and resonance frequency.In conclusion,halving the porous layer’s thickness while incorporating an air layer and single MPP proved more effective than using a thick porous material.This approach not only reduces costs and space requirements but also enhances low-frequency performance.The study highlights the precision of numerical methods like FEM,reducing the need for resource-intensive direct methods and associated laboratory expenses.展开更多
Remote control enzyme technology is widely used today through resonance. In this study, we showed that the use of frequencies of the catalase enzyme itself to increase enzymatic rate is successful not only in test tub...Remote control enzyme technology is widely used today through resonance. In this study, we showed that the use of frequencies of the catalase enzyme itself to increase enzymatic rate is successful not only in test tubes but also remotely. The present study also suggests that, under optimal temperature, the use of bovine catalase frequency (the specific frequency of that enzyme) has a superior rate promoting vibration than the human catalase frequency, and so increases very significantly the chemical rate of bovine catalase (about 120% at 40˚C). It also suggests that bovine catalase subjected to bovine and human frequencies with catalase bound NADP+ experienced more resonance weight towards NADP+ and so were more slowly reduced back to catalase bound NADPH, increasing compound II formation rate, and slowing down the catalase activity rate.展开更多
Objective To observe postoperative effect of electroacupuncture（EA） of different frequencies in acupuncture anesthesia combined with drugs on patients undergoing thyroid surgery.Methods One hundred and twenty patien...Objective To observe postoperative effect of electroacupuncture（EA） of different frequencies in acupuncture anesthesia combined with drugs on patients undergoing thyroid surgery.Methods One hundred and twenty patients undergoing thyroid surgery were randomly divided into a 2Hz electroacupuncture anesthesia group（group A）,a 100 Hz electroacupuncture anesthesia group（group B）,a 2Hz/100 Hz electroacupuncture anesthesia group（group C） and a cervical plexus block group（group D） in accordance with the random number table method,with 30 patients in each group.In group A,group B and group C,electroacupuncture was applied at bilateral Futu（扶突 LI 18）,Hegu（合谷 LI 4） and Neiguan（内关 PC 6） at frequencies of 2 Hz,100 Hz and 2 Hz/100 Hz respectively for 30 min.The needles were retained till the end of the surgery.Dolantin and atropine were intramuscularly injected In group D,bilateral cervical plexus block was produced with a mixture of1%lidocaine and 0.375%bupivicaine.Before surgery,pain threshold and threshold of pain tolerance were determined;during surgery,the duration of surgery was recorded;and after surgery,QOLS（Quality Of Life Score） and PHS（Prince-Henry Score） were assessed.Results PHS in group A,group B and group C were lower than that in group D,respectively（0.20±0.41,0.17±0.38,0.10±0.31 vs 0.40±0.50,P〈0.01）,and PHS in group C was lower than those in group A and group B,respectively（both P〈0.01）.QOLS in group A,group B and group C were higher than that in group D,respectively（9.97±1.07,9.97±2.27,10.40±1.45 vs 9.73±1.41,P〈0.05,P〈0.01）,and QOLS in group C was higher than those in group A and group B,respectively（both P〈0.05）.Conclusion Acupuncture anesthesia combined with drugs has better postoperative effect than drug anesthesia.Electroacupuncture of different frequencies can significantly improve general quality of life of patients,so patients recover well after thyroid surgery.As patients in group C suffered from the slightest pain with the highest quality of life,they recovered best within the shortest time.Electroacupuncture at frequency of 2 Hz/100 Hz can better play postoperative analgesic effect.展开更多
In many engineering applications such as mining,geotechnical and petroleum industries,drilling operation is widely used.The drilling operation produces sound by-product,which could be helpful for preliminary estimatio...In many engineering applications such as mining,geotechnical and petroleum industries,drilling operation is widely used.The drilling operation produces sound by-product,which could be helpful for preliminary estimation of the rock properties.Nevertheless,determination of rock properties is very difficult by the conventional methods in terms of high accuracy,and thus it is expensive and timeconsuming.In this context,a new technique was developed based on the estimation of rock properties using dominant frequencies from sound pressure level generated during diamond core drilling operations.First,sound pressure level was recorded and sound signals of these sound frequencies were analyzed using fast Fourier transform (FFT).Rock drilling experiments were performed on five different types of rock samples using computer numerical control (CNC) drilling machine BMV 45 T20.Using simple linear regression analysis,mathematical equations were developed for various rock properties,i.e.uniaxial compressive strength,Brazilian tensile strength,density,and dominant frequencies of sound pressure level.The developed models can be utilized at early stage of design to predict rock properties.展开更多
[Objective] The aim was to study the effects of sound waves with different types and frequency characteristics on the growth of cowpea（Vigna unguiculata）during seedling stage.[Method] The insect-music mixed sound（M...[Objective] The aim was to study the effects of sound waves with different types and frequency characteristics on the growth of cowpea（Vigna unguiculata）during seedling stage.[Method] The insect-music mixed sound（MI）,cuckoo acoustic song,cricket acoustic song,single 400 Hz frequency sound wave,F5 and Fn sound waves composed of different frequencies were designed to investigate their effects on height and weight of cowpea seedling,and experimental data were statistically analyzed and multiple-compared by EXCEL.[Result] After treatment by sound waves with six different types and frequencies,the growth situations of cowpea were better than that in control.This indicated that sound waves could significantly promote height growth of plant.The treatments with good growth-promotion effect included 400 Hz frequency sound wave,cuckoo acoustic song and cricket acoustic song,followed by MI,Fn and F5.Cuckoo and cricket acoustic song treatment could promote the weight of cowpea seedling during seedling stage.[Conclusion] Sound waves with different types and frequency characteristics had significant growth-promotion effect on growth of cowpea during seedling stage,but their effects were different.展开更多
[Objective] The aim was to investigate the effects of sound wave on propagation of Chlorella pyrenoidosa to explore the optimal frequency for Chlorella pyrenoidosa.[Method] In the research,Chlorella pyrenoidosa was cu...[Objective] The aim was to investigate the effects of sound wave on propagation of Chlorella pyrenoidosa to explore the optimal frequency for Chlorella pyrenoidosa.[Method] In the research,Chlorella pyrenoidosa was cultured for 7 d with sound waves at different frequencies and a control group was set to study effects of sound wave at different frequencies on growth of Chlorella pyrenoidosa.[Result] Growth of Chlorella pyrenoidosa was significantly improved by sound wave,especially for wave at 400 Hz.[Conclusion] Chlorella pyrenoidosa propagation would be promoted by sound wave at certain frequencies.展开更多
基金Supported by National Natural Science Foundation of China(No.82271062)Tianjin Key Medical Discipline(Specialty)Construction Project(No.TJYXZDXK-037A)Tianjin Science and Technology Bureau(No.21JCZDJC01010).
文摘AIM:To compare the efficacy of 3%diquafosol sodium(DQS)eye drops at different frequencies in dry eye(DE)after femtosecond laser-assisted in situ keratomileusis(FS-LASIK).METHODS:In this prospective study,DE patients after FS-LASIK were randomly divided into two groups.All patients were administered routine anti-inflammatory and anti-infective drugs after FS-LASIK.Additionally,both groups were treated with DQS,at frequencies of 4(DQS4 group)and 6(DQS6 group)times daily.Corneal fluorescein staining(CFS)score,non-invasive tear breakup time(NIBUT),tear meniscus height(TMH),lipid layer thickness(LLT),and incomplete blink rate(IBR)were assessed in patients preoperatively and at 1wk,1,and 3mo postoperatively.The Ocular Surface Disease Index(OSDI)questionnaire was also administered.RESULTS:Totally 119 patients(238 eyes)were randomly divided into the DQS4 group(60 individuals with 120 eyes)and DQS6 group(59 individuals with 118 eyes).From 1wk to 1mo after FS-LASIK,the CFS score in the DQS6 group decreased with statistical significance(P=0.014),while the DQS4 group showed an upward trend.Comparing with preoperative values,the NIBUT of both groups was significantly prolonged at various time points after FS-LASIK(P<0.05).Within 1mo post FS-LASIK,both groups had significantly higher OSDI scores compared with preoperative values(P<0.05).At postoperative 3mo,the DQS4 group recovered to a level similar to that before surgery(P>0.05),while the DQS6 group remained a little higher than preoperative values(P>0.05).The TMH levels in the DQS4 group increased significantly at 1wk postoperatively(P<0.05),while there was no statistically significant change in the TMH levels in the DQS6 group(P>0.05).There was no significant difference in IBR and LLT between the two groups within 1mo postoperatively.At postoperative 3mo,the LLT in the DQS4 group was significantly higher than that in the DQS6 group(P<0.05).CONCLUSION:Within 1mo post-FS-LASIK,applying DQS six times daily is superior to four daily applications in improving CFS score,and in increasing NIBUT meanwhile.After 1mo,applying DQS four times daily also effectively alleviate DE symptoms and improve DE signs.Therefore,we recommend DE patients using DQS eye drops 6 times daily within 1mo after FS-LASIK,and maintaining it 4 times daily until 3mo postoperatively.
基金supported by the Open Fund of Key Laboratory of Geological Hazards on Three Gorges Reservoir Area(China Three Gorges University)of the Ministry of Education(Grant Nos.2022KDZ14 and 2022KDZ15)the Open Fund of Badong National Observation and Research Station of Geohazards(Grant No.BNORSG-202304)+3 种基金the Science and Technology Project of Department of Natural Resources of Hubei Province(Grant No.ZRZY2024KJ15)the Natural Science Foundation of Hubei Province(Grant No.2022CFB557)the National Natural Science Foundation of China(Grant No.42107489)the 111 Project of Hubei Province(Grant No.2021EJD026)。
文摘The precision of landslide displacement prediction is crucial for effective landslide prevention and mitigation strategies.However,the role of surface monitoring frequency in influencing prediction accuracy has been largely neglected.This study examined the effect of varying monitoring frequencies on the accuracy of displacement predictions by using the Baijiabao landslide in the Three Gorges Reservoir Area(TGRA)as a case study.We collected surface automatic monitoring data at different intervals,ranging from daily to monthly.The Ensemble Empirical Mode Decomposition(EEMD)algorithm was utilized to dissect the accumulated displacements into periodic and trend components at each monitoring frequency.Polynomial fitting was applied to forecast the trend component while the periodic component was predicted with two state-of-the-art neural network models:Long Short-Term Memory(LSTM)and Gated Recurrent Unit(GRU).The predictions from these models were integrated to derive cumulative displacement forecasts,enabling a comparative analysis of prediction accuracy across different monitoring frequencies.The results demonstrate that the proposed models achieve high accuracy in landslide displacement forecasting,with optimal performance observed at moderate monitoring intervals.Intriguingly,the daily mean average error(MAE)decreases sharply with increasing monitoring frequency,reaching a plateau.These findings were corroborated by a parallel analysis of the Bazimen landslide,suggesting that moderate monitoring intervals of approximately 7 to 15 days are most conducive to achieving enhanced prediction accuracy compared to both daily and monthly intervals.
文摘Using real fields instead of complex ones, it was recently claimed, that all fermions are made of pairs of coupled fields (strings) with an internal tension related to mutual attraction forces, related to Planck’s constant. The solution to Dirac equation gives four, real, 2-vectors solutions ψ1=(U1D1)ψ2=(U2D2)ψ3=(U3D3)ψ4=(U4D4)where (ψ1,ψ4) are coupled via linear combinations to yield spin-up and spin-down fermions. Likewise, (ψ2,ψ3) are coupled via linear combinations to represent spin-up and spin-down anti-fermions. Here, a deeper investigation of the free fermion internal frequency is discussed, hinting to an exchange interaction between the two components of which a fermion is made of. An upper limit estimate is given to the strength of this interaction.
基金the Fund of Science and Technology Innovation Project of Chinese Academy of Chinese Medical Sciences Project:Self-service Acupuncture Smoking Cessation Research and Development(No.CI2021A03506)Fund of Capital Health Development Special Research Project:Research on Development and Clinical Applicalion of Wrist Acupuncture Smoking Cessation Instrument(No.2022-1-4281)。
文摘OBJECTIVE:To observe the effect of different acupuncture frequencies on the abstinence rate which could be used as a reference for optimizing acupuncture cessation programs.METHODS:From July 2018 to June 2022,a total of 220 smokers were recruited based on inclusion criteria and randomly divided into the high-frequency acupuncture group(HF group,n=110):5 times a week from the 1st to the 4th week,from weeks 5 to 8,three times a week and the low-frequency acupuncture group(LF group,n=110):3 times a week from the 1st to the 4th week,from weeks 5 to 8,twice a week,then treated for 8 weeks and followup at 1 month in Beijing.RESULTS:In total,162 subjects completed the whole study with a drop-out rate of 20.45%.The expiratory CO point abstinence rate was HF group 53/110(48.18%)vs LF group 41/110(37.27%)in Week 8(P=0.102)and HF group 46/110(41.82%)vs LF group 45/110(40.91%)in Week 12(P=0.891)and the HF acupuncture and LF acupuncture were nearly equal in the 8-week abstinence rate.In addition,both HF and LF acupuncture significantly reduced Fagerstr?m test for nicotine dependence scale(FTND)scores(P<0.05),Minnesota nicotine withdrawal scale(MNWS)scores(P<0.05),and Brief Questionnaire of Smoking Urges scale(QSU-Brief)scores(P<0.05),but HF acupuncture showed some superiority over LF acupuncture in relieving patients'smoking cravings(P<0.05).CONCLUSIONS:The study initially showed that both high-frequency acupuncture and low-frequency acupuncture treatment were safe and effective on smoking cessation for 8 weeks,but high-frequency acupuncture was advantageous in reducing smoking cravings.More accurate acupuncture frequency needs to be validated through larger clinical studies to optimize acupuncture smoking cessation programs.
基金China National Social Science Fund Project,19BTY052.
文摘Background:Anxiety and depression are prevalent among university students,calling for effec-tive non-pharmacological interventions.Tai Chi shows potential in reducing these symptoms,but research on its effects at different frequencies in younger populations is limited.This study compared the impacts of high-(5 ses-sions/week),medium-(3 sessions/week),and low-frequency(2 sessions/week)24-form Tai Chi on college students’anxiety/depression,versus a control group.Methods:A randomized controlled trial(RCT)included 120 university students with mild-to-moderate anxiety/depression,randomly assigned to 4 groups(30 each).The 8-week intervention used the Self-Rating Anxiety Scale(SAS)and Self-Rating Depression Scale(SDS)for assessments at baseline,week 4,and week 8.Analyses included paired t-tests(within-group changes),one-way ANOVA(between-group differences),repeated measures ANOVA(RM-ANOVA,temporal changes),and Mixed Model for Repeated Measures(MMRM,longitudinal changes with missing data).Results:All intervention groups had significant SAS/SDS reductions:high-frequency group(SAS:20.4%,t=7.21,p<0.001;SDS:22.1%,t=6.92,p<0.001)>medium-frequency group(SAS:18.3%,t=5.06,p<0.001;SDS:19.8%,t=5.18,p<0.001)>low-frequency group(SAS:15.2%,t=4.09,p<0.001;SDS:17.4%,t=4.67,p<0.001).No changes were seen in the control group.The high-frequency group outperformed the low-frequency and control groups(p<0.05);RM-ANOVA and MMRM confirmed sustained,time-dependent effects,with the high-frequency group being optimal.Conclusion:24-form Tai Chi effectively reduces college students’anxiety/depression,with efficacy increasing with frequency(high>medium>low).The high-frequency protocol(5 sessions/week)is the most effective non-pharmacological intervention,and MMRM confirms its sustained efficacy.
基金supported by Henan Province Science and Technology Research Funding Project(No.222102320129)the Key Research Project of Henan Higher Education Institutions(Grant Nos.22A560004,22A56005).
文摘As an evaluation index,the natural frequency has the advantages of easy acquisition and quantitative evaluation.In this paper,the natural frequency is used to evaluate the performance of external cable reinforced bridges.Numerical examples show that compared with the natural frequencies of first-order modes,the natural frequencies of higher-order modes are more sensitive and can reflect the damage situation and external cable reinforcement effect of T-beam bridges.For damaged bridges,as the damage to the T-beam increases,the natural frequency value of the bridge gradually decreases.When the degree of local damage to the beam reaches 60%,the amplitude of natural frequency change exceeds 10%for the first time.The natural frequencies of the firstorder vibration mode and higher-order vibration mode can be selected as indexes for different degrees of the damaged T-beam bridges.For damaged bridges reinforced with external cables,the traditional natural frequency of the first-order vibration mode cannot be used as the index,which is insensitive to changes in prestress of the external cable.Some natural frequencies of higher-order vibration modes can be selected as indexes,which can reflect the reinforcement effect of externally prestressed damaged T-beam bridges,and its numerical value increases with the increase of external prestressed cable force.
基金financially supported by the National Key Research and Development Program of China(2022YFC2406600 and 2020YFB2009000)the Program for Innovation Team of Shaanxi Province(2021TD-23)。
文摘Acoustofluidics is a term describing the class of phenomena in which mechanical or acoustic vibrations induce a deformation or a flow in a fluid.Many deficiencies in our understanding of these phenomena remain to be addressed,with respect to the fundamental theoretical framework as well as in numerous applications.In this regard,the frequency of external forcing is a key parameter.Owing to the low cost,substantial magnitude,and versatility associated with acoustofluidic phenomena at audible frequencies,studies of these phenomena in the audible range have emerged with increasing amount in recent years and have attracted considerable attention.However,compared with studies focusing on the ultrasonic frequency domain,critical features and information specific to audible acoustofluidics remain dispersed across many independent publications,and a systematic integration of the literature on this topic is necessary.Accordingly,this review summarizes the basic theory and methods for generating vibrations in the audible range,presents various applications thereof in biology,chemistry,and other fields,and provides a high-level overview of the current status of the topic to motivate developing interesting proposals for further research in this field of study.
基金supported by the Natural Science Foundation of Shanxi Provincial(Grant No.202203021211153)the Basic Research Program of Shanxi Province(Grant No.202203021212284)+2 种基金Open Foundation of the State Key Laboratory of Satellite Navigation System and Equipment Technology(Grant No.CEPNT2022B07)the Open Foundation of the State Key Laboratory of Geodesy and Earth's Dynamics(Grant No.SKLGED2022-3-4)the research on application technology of Beidou in the field of energy and power(Grant No.CEEC2022-ZDYF-01).
文摘With the gradual development and modernization of satellite navigation systems,using observation information from multi-GNss has become one of the hot-spot issues in recent years.Multi-system loose combinations form double-difference observation equations within their respective systems,and the positioning effect is improved.However,the interchangeability and compatible interoperability between global navigation satellite systems(GNSS)cannot be truly realized.At the same time,when the number of visible satellites decreases abruptly,the positioning performance deteriorates sharply.This paper focuses on the GNsS multi-system tight combination relative positioning technique,gives a mathe-matical model of multi-system tight combination relative positioning considering differential inter-system bias(DISB),and analyzes the time-varying characteristics of DISB at overlapping and non-overlapping frequencies among GPS/Galileo,GPS/BDS,and GPS/QZSS in terms of receiver brand,tem-perature,and receiver restart.The GNsS tight combination relative positioning performance is verified by static data from Curtin University and dynamic data measured at Taiyuan University of Technology.The results show that compared with loose combination,the ambiguity-fixed rate increases from 62.18%to 97.60%for static data and from 74.97%to 99.53%for dynamic data when the elevation mask angle is 50°,resulting in a significant improvement in positioning performance.
基金supported by the National Key Research and Development Program of China under Grant 2023YFB2407400。
文摘In the cascaded H-bridge inverter(CHBI)with supercapacitor and dc-dc stage,inherent second-order harmonic power flows through each submodule(SM),causing fluctuations in both the dc-link voltage and the dc-dc current.There exist limitations in handling these fluctuations at variable output frequencies when employing proportional-integral(PI)control to the dc-dc stage.This paper aims to coordinately control these second-order harmonic voltage and current fluctuations in the CHBI.The presented method configures a specific second-order harmonic voltage reference,equipped with a maximum voltage fluctuation constraint and a suitable phase,for the dc-dc stage.A PI-resonant controller is used to track the configured reference.This allows for regulating the second-order harmonic fluctuation in the average dc-link voltage among the SMs within a certain value.Importantly,the second-order harmonic fluctuation in the dc-dc current can also be reduced.Simulation and experimental results demonstrate the effectiveness of the presented method.
基金Project supported by the National Natural Science Foundation of China(Grant No.92271113)the Fundamental Research Funds for the Central Universities(Grant No.2022CDJQY-003)+1 种基金Chongqing Entrepreneurship and Innovation Support Program for Overseas Returnees(Grant No.CX2022004)the Fund from Shanghai Engineering Research Center of Space Engine(Grant No.17DZ2280800).
文摘This paper deals with wave propagation and power coupling in blue-core helicon plasma driven by various antennas and frequencies.It is found that compared to non-blue-core mode,for blue-core mode,the wave can propagate in the core region,and it decays sharply outside the core.The power absorption is lower and steeper in radius for blue-core mode.Regarding the effects of antenna geometry for blue-core mode,it shows that half helix antenna yields the strongest wave field and power absorption,while loop antenna yields the lowest.Moreover,near axis,for antennas with m=+1,the wave field increases with axial distance.In the core region,the wave number approaches to a saturation value at much lower frequency for non-blue-core mode compared to blue-core mode.The total loading resistance is much lower for blue-core mode.These findings are valuable to understanding the physics of blue-core helicon discharge and optimizing the experimental performance of blue-core helicon plasma sources for applications such as space propulsion and material treatment.
基金co-supported by the National Key R&D Program of China(No.2020YFC2201001)the Shenzhen Science and Technology Program(No.20210623091808026).
文摘The bipolar ionic liquid thruster employs ionic liquid as a propellant to discharge positively and negatively charged high-energy particles under an alternating current(AC)power source,effectively suppressing electrochemical reaction and ensuring charge neutrality.Determining an optimal AC supply power source frequency is critical for sustained stable thruster operation.This study focuses on the emission characteristics of the ionic liquid thruster under varied AC conditions.The AC power supply was set within the frequency range of 0.5-64 Hz,with eight specific frequency conditions selected for experimentation.The experimental results indicate that the thruster operates steadily within a voltage range of±1470 to±1920 V,with corresponding positive polarity current ranging from 0.41 to 4.91μA and negative polarity current ranging from−0.49 to−4.10μA.During voltage polarity switching,an emission delay occurs,manifested as a prominent peak signal caused by circuit capacitance characteristics and a minor peak signal resulting from liquid droplets.Extended emission test was conducted at 16 Hz,demonstrating approximately 1 h and 50 min of consistent emission before intermittent discharge.These findings underscore the favorable impact of AC conditions within the 8-16 Hz range on the self-neutralization capability of the ionic liquid thruster.
基金the National Natural Science Foundation of China(https://www.nsfc.gov.cn/,Project No.11972179)the Natural Science Foundation of Guangdong Province(http://gdstc.gd.gov.cn/,No.2020A1515010685)the Department of Education of Guangdong Province(http://edu.gd.gov.cn/,No.2020ZDZX2008).
文摘The boundary element method(BEM)is a popular method for solving acoustic wave propagation problems,especially those in exterior domains,owing to its ease in handling radiation conditions at infinity.However,BEM models must meet the requirement of 6–10 elements per wavelength,using the conventional constant,linear,or quadratic elements.Therefore,a large storage size of memory and long solution time are often needed in solving higher-frequency problems.In this work,we propose two new types of enriched elements based on conventional constant boundary elements to improve the computational efficiency of the 2D acoustic BEM.The first one uses a plane wave expansion,which can be used to model scattering problems.The second one uses a special plane wave expansion,which can be used tomodel radiation problems.Five examples are investigated to showthe advantages of the enriched elements.Compared with the conventional constant elements,the new enriched elements can deliver results with the same accuracy and in less computational time.This improvement in the computational efficiency is more evident at higher frequencies(with the nondimensional wave numbers exceeding 100).The paper concludes with the potential of our proposed enriched elements and plans for their further improvement.
基金supported by the National Natural Science Fund of China(82374561,82174490,81873360)the Zhejiang Medical and Health Science and Technology Program(2021RC098)the Research Project of Zhejiang Chinese Medical University(2022JKZKTS44).
文摘Objective:Electroacupuncture(EA)is an alternative treatment option for pain.Different frequencies of EA have different painrelieving effects;however,the central mechanism is still not well understood.Methods:The Fos2A-iCreER(TRAP):Ai9 mice were divided into three groups(sham,2 Hz,and 100 Hz).The mice were intraperitoneally injected with 4-hydroxytamoxifen(4-OHT)immediately after EA at Zusanli(ST36)for 30 min to record the activated neurons.One week later,the mice were sacrificed,and the number of TRAP-treated neurons activated by EA in the thalamus,amygdala,cortex,and hypothalamus was determined.Results:In the cortex,2 Hz EA activated more TRAP-treated neurons than 100 Hz EA did in the cingulate cortex area 1(Cg1)and primary somatosensory cortex(S1),and 2 and 100 Hz EAs did not differ from sham EA.TRAP-treated neurons activated by 2 Hz EA were upregulated in the insular cortex(IC)and secondary somatosensory cortex(S2)compared with those activated by 100 Hz and sham EA.In the thalamus,the number of TRAP-treated neurons activated by 2 Hz EA was elevated in the paraventricular thalamic nucleus(PV)compared with those activated by sham EA.In the ventrolateral thalamic nucleus(VL),the number of TRAPtreated neurons activated by 2 Hz EA was significantly upregulated compared with those activated by 100 Hz EA,and sham EA showed no difference compared with 2 or 100 Hz EA.TRAP-treated neurons were more frequently activated in the ventral posterolateral thalamic nucleus(VPL)by 2 Hz EA than by 100 Hz or sham EA.Conclusions:Low-frequency EA ST36 effectively activates neurons in the Cg1,S1,S2,IC,VPL,PV,and VL.The enhanced excitability of the aforementioned nuclei induced by low-frequency EA may be related to its superior efficacy in the treatment of neuropathological pain.
文摘Recently,abacafibers have become the focus of specialized research due to their intriguing characteristics,with their outstanding mechanical properties being a particularly notable.In the conducted study,the abacafibers underwent a preliminary treatment process involving an alkaline solution,which was composed of 0.5%sodium hydroxide(NaOH)and 50%acetic acid(CH3COOH).This process entailed immersing eachfiber in the solution for a period of one hour.This treatment led to a 52.36%reduction in lignin content compared to the levels before treatment,resulting in a dramatic decrease in the full width at half maximum(FWHM)in the XRD spectra from 1.13 to 0.13.This change indicates that thefibers became more crystalline following the treatment.The abacafibers were also characterized using BET(Brunauer Emmett Teller)measurements,which revealed that the aver-age pore length ranged from 33–49 nm and the surface area was between 13–28 m^(2)·g^(-1).The morphology of the abacafiber after alkali an hydrolisis treatment(AFAH)appeared rougher and more uniform.DMA measurements revealed a significant rise in the storage modulus of the singlefiber post-treatment,with dependencies on both frequency and temperature.AFAH exhibited an optimal absorption coefficient ofα=0.9 for frequencies above 2500 Hz.The combined effect of alkalization and hydrolyzation treatments,while resulting in an enhancement in the mechanical properties of thefibers,also reduced high-intensity noise produced by sources such as machin-ery,aircraft takeoffs and landings,etc.,across a broader working frequency range.
文摘Mitigating low-frequency noise poses a significant challenge for acoustic engineers,due to their long wavelength,with conventional porous sound absorbers showing limitations in attenuating such noise.An effective strategy involves combining porous materials with micro-perforated plates(MPP)to address this issue.Given the significant impact of structural variables like panel thickness,hole diameter,and air gap on the acoustic characteristics of MPP,achieving the optimal condition demands numerous sample iterations.The impedance tube’s considerable expense for sound absorption measurement and the substantial cost involved in fabricating each sample using a 3D printer underscore the advantage of utilizing simulation methods to attain the optimal state.This study focuses on optimizing low-frequency enhancement by investigating key parameters.Using the Finite Element Numerical Method(FEM)in COMSOL software,a composite panel was constructed comprising date palm fiber layers,an intervening air layer,and MPP.The study explored the arrangement of these layers and the impact of parameters like hole diameter,plate thickness,and perforation ratio on acoustic behavior.The selected optimal parameter at each stage was consistently maintained for subsequent steps.Results revealed that layer arrangement significantly influenced acoustic characteristics.Placing the MPP layer before the porous material yielded superior low-frequency performance.Optimizing low-frequency behavior involved reducing hole diameter and perforation ratio while increasing plate thickness.Elevating the porous material’s thickness relative to the air layer behind the MPP enhanced absorption peak and resonance frequency.In conclusion,halving the porous layer’s thickness while incorporating an air layer and single MPP proved more effective than using a thick porous material.This approach not only reduces costs and space requirements but also enhances low-frequency performance.The study highlights the precision of numerical methods like FEM,reducing the need for resource-intensive direct methods and associated laboratory expenses.
文摘Remote control enzyme technology is widely used today through resonance. In this study, we showed that the use of frequencies of the catalase enzyme itself to increase enzymatic rate is successful not only in test tubes but also remotely. The present study also suggests that, under optimal temperature, the use of bovine catalase frequency (the specific frequency of that enzyme) has a superior rate promoting vibration than the human catalase frequency, and so increases very significantly the chemical rate of bovine catalase (about 120% at 40˚C). It also suggests that bovine catalase subjected to bovine and human frequencies with catalase bound NADP+ experienced more resonance weight towards NADP+ and so were more slowly reduced back to catalase bound NADPH, increasing compound II formation rate, and slowing down the catalase activity rate.
文摘Objective To observe postoperative effect of electroacupuncture（EA） of different frequencies in acupuncture anesthesia combined with drugs on patients undergoing thyroid surgery.Methods One hundred and twenty patients undergoing thyroid surgery were randomly divided into a 2Hz electroacupuncture anesthesia group（group A）,a 100 Hz electroacupuncture anesthesia group（group B）,a 2Hz/100 Hz electroacupuncture anesthesia group（group C） and a cervical plexus block group（group D） in accordance with the random number table method,with 30 patients in each group.In group A,group B and group C,electroacupuncture was applied at bilateral Futu（扶突 LI 18）,Hegu（合谷 LI 4） and Neiguan（内关 PC 6） at frequencies of 2 Hz,100 Hz and 2 Hz/100 Hz respectively for 30 min.The needles were retained till the end of the surgery.Dolantin and atropine were intramuscularly injected In group D,bilateral cervical plexus block was produced with a mixture of1%lidocaine and 0.375%bupivicaine.Before surgery,pain threshold and threshold of pain tolerance were determined;during surgery,the duration of surgery was recorded;and after surgery,QOLS（Quality Of Life Score） and PHS（Prince-Henry Score） were assessed.Results PHS in group A,group B and group C were lower than that in group D,respectively（0.20±0.41,0.17±0.38,0.10±0.31 vs 0.40±0.50,P〈0.01）,and PHS in group C was lower than those in group A and group B,respectively（both P〈0.01）.QOLS in group A,group B and group C were higher than that in group D,respectively（9.97±1.07,9.97±2.27,10.40±1.45 vs 9.73±1.41,P〈0.05,P〈0.01）,and QOLS in group C was higher than those in group A and group B,respectively（both P〈0.05）.Conclusion Acupuncture anesthesia combined with drugs has better postoperative effect than drug anesthesia.Electroacupuncture of different frequencies can significantly improve general quality of life of patients,so patients recover well after thyroid surgery.As patients in group C suffered from the slightest pain with the highest quality of life,they recovered best within the shortest time.Electroacupuncture at frequency of 2 Hz/100 Hz can better play postoperative analgesic effect.
文摘In many engineering applications such as mining,geotechnical and petroleum industries,drilling operation is widely used.The drilling operation produces sound by-product,which could be helpful for preliminary estimation of the rock properties.Nevertheless,determination of rock properties is very difficult by the conventional methods in terms of high accuracy,and thus it is expensive and timeconsuming.In this context,a new technique was developed based on the estimation of rock properties using dominant frequencies from sound pressure level generated during diamond core drilling operations.First,sound pressure level was recorded and sound signals of these sound frequencies were analyzed using fast Fourier transform (FFT).Rock drilling experiments were performed on five different types of rock samples using computer numerical control (CNC) drilling machine BMV 45 T20.Using simple linear regression analysis,mathematical equations were developed for various rock properties,i.e.uniaxial compressive strength,Brazilian tensile strength,density,and dominant frequencies of sound pressure level.The developed models can be utilized at early stage of design to predict rock properties.
基金Supported by Major Scientific and Technological Special Projects in Zhejiang Province(2008C12056)~~
文摘[Objective] The aim was to study the effects of sound waves with different types and frequency characteristics on the growth of cowpea（Vigna unguiculata）during seedling stage.[Method] The insect-music mixed sound（MI）,cuckoo acoustic song,cricket acoustic song,single 400 Hz frequency sound wave,F5 and Fn sound waves composed of different frequencies were designed to investigate their effects on height and weight of cowpea seedling,and experimental data were statistically analyzed and multiple-compared by EXCEL.[Result] After treatment by sound waves with six different types and frequencies,the growth situations of cowpea were better than that in control.This indicated that sound waves could significantly promote height growth of plant.The treatments with good growth-promotion effect included 400 Hz frequency sound wave,cuckoo acoustic song and cricket acoustic song,followed by MI,Fn and F5.Cuckoo and cricket acoustic song treatment could promote the weight of cowpea seedling during seedling stage.[Conclusion] Sound waves with different types and frequency characteristics had significant growth-promotion effect on growth of cowpea during seedling stage,but their effects were different.
基金Supported by Zhejiang Major Science and Technology Program(2008C12056)Zhejiang Science Innovation Plan for Undergraduate(2011R415023)~~
文摘[Objective] The aim was to investigate the effects of sound wave on propagation of Chlorella pyrenoidosa to explore the optimal frequency for Chlorella pyrenoidosa.[Method] In the research,Chlorella pyrenoidosa was cultured for 7 d with sound waves at different frequencies and a control group was set to study effects of sound wave at different frequencies on growth of Chlorella pyrenoidosa.[Result] Growth of Chlorella pyrenoidosa was significantly improved by sound wave,especially for wave at 400 Hz.[Conclusion] Chlorella pyrenoidosa propagation would be promoted by sound wave at certain frequencies.
