期刊文献+
共找到7,986篇文章
< 1 2 250 >
每页显示 20 50 100
Botulinum toxin type A for treating chronic low back pain:A double blinded randomized control study
1
作者 Mantu Jain Shahnawaz Khan +2 位作者 Paulson Varghese Sujit Kumar Tripathy Manaswini Mangaraj 《World Journal of Methodology》 2024年第3期119-125,共7页
BACKGROUND Low back pain(LBP)is a prevalent issue that orthopedic surgeons frequently address in the outpatient setting.LBP can arise from various causes,with stiffness in the paraspinal muscles being a notable contri... BACKGROUND Low back pain(LBP)is a prevalent issue that orthopedic surgeons frequently address in the outpatient setting.LBP can arise from various causes,with stiffness in the paraspinal muscles being a notable contributor.The administration of Botulinum toxin type A(BoNT-A)has been found to alleviate back pain by relaxing these stiff muscles.While BoNT-A is approved for use in numerous conditions,a limited number of randomized clinical trials(RCTs)validate its efficacy specifically for treating LBP.AIM To study the safety and the efficacy of BoNT-A in minimizing pain and improving functional outcomes in patients of chronic LBP(CLBP).METHODS In this RCT,adults aged 18-60 years with mechanical LBP persisting for at least six months were enrolled.Participants were allocated to either the Drug group,receiving 200 Ipsen Units(2 mL)of BoNT-A,or the Control group,which received a 2 mL placebo.Over a 2-month follow-up period,both groups were assessed using the Visual Analog Scale(VAS)for pain intensity and the Oswestry Disability Index(ODI)for disability at the start and conclusion of the study.A decrease in pain by 50%was deemed clinically significant.RESULTS The study followed 40 patients for two months,with 20 in each group.A clinically significant reduction in pain was observed in 36 participants.There was a statistically significant decrease in both VAS and ODI scores in the groups at the end of two months.Nonetheless,when comparing the mean score changes,only the reduction in ODI scores(15 in the placebo group vs 16.5 in the drug group,clinically insignificant)was statistically significant(P=0.012),whereas the change in mean VAS scores was not significant(P=0.45).CONCLUSION The study concludes that BoNT-A does not offer a short-term advantage over placebo in reducing pain or improving LBP scores in CLBP patients. 展开更多
关键词 Botulinum toxin type A Chronic low back pain Randomized control study Double-blinded Pain management Therapeutic efficacy
下载PDF
Austenite Recrystallization and Controlled Rolling of Low Carbon Steels 被引量:4
2
作者 DU Lin-xiu ZHANG Zhong-ping SHE Guang-fu LIU Xiang-hua WANG Guo-dong 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2006年第3期31-35,50,共6页
The dynamic recrystallization and static recrystallization in a low carbon steel were investigated through single-pass and double-pass experiments. The results indicate that as the deformation temperature increases an... The dynamic recrystallization and static recrystallization in a low carbon steel were investigated through single-pass and double-pass experiments. The results indicate that as the deformation temperature increases and the strain rate decreases, the shape of the stress-strain curve is changed from dynamic recovery shape to dynamic recrystallization shape. The austenite could not recrystallize within a few seconds after deformation at temperature below 900 ℃. According to the change in microstructure during deformation, the controlled rolling of low carbon steel can be divided into four stages: dynamic recrystallization, dynamic recovery, strain-induced ferrite transformation, and rolling in two-phase region. According to the microstructure after deformation, the controlled rolling of low carbon steel can be divided into five regions: non-recrystallized austenite, partly-recrystallized austenite, fully-recrystallized austenite, austenite to ferrite transformation, and dual phase. 展开更多
关键词 RECRYSTALLIZATION low carbon steel AUSTENITE strain-induced transformation controlled rolling
下载PDF
Controlled Rolling and Cooling Process for Low Carbon Cold Forging Steel 被引量:4
3
作者 李壮 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2010年第1期89-93,共5页
Effect of controlled rolling and cooling process on the mechanical properties of low carbon cold forging steel was investigated for different processing parameters of a laboratory hot rolling mill. The results show th... Effect of controlled rolling and cooling process on the mechanical properties of low carbon cold forging steel was investigated for different processing parameters of a laboratory hot rolling mill. The results show that the specimens with fast cooling after hot rolling exhibit very good mechanical properties, and the improvement of the mechanical properties can be attributed mainly to the ferrite-grain refinement. The mechanical properties increase with decreasing final cooling temperature within the range from 670 ℃ to 570 ℃ due to the finer interlamellar spacing of pearlite colony. The specimen with fast cooling after low temperature rolling shows the highest values of the mechanical properties. The effect of the ferrite grain size on the mechanical properties was greater than that of pearlite morphology in the present study. The mechanical properties of specimens by controlled rolling and cooling process without thermal treatment were greatly superior to that of the same specimens by the conventional rolling, and their tensile strength reached 490 MPa grade even in the case of low temperature rolling without controlled rolling. It might be expected to realize the substitution medium-carbon by low-carbon for 490 MPa grade cold forging steel with controlled rolling and cooling process. 展开更多
关键词 controlled rolling and cooling process low carbon cold forging steel fast cooling low temperature rolling the ferrite-grain refineme
下载PDF
Properties of Rapid Hardening Controlled Low Strength Material Made of Recycled Fine Aggregate from Urban Red Brick Construction Waste
4
作者 Jin Ran Jinxi Zhang 《World Journal of Engineering and Technology》 2017年第2期188-197,共10页
In some cases of emergency backfill engineering projects, traditional backfill materials cannot meet the requirements of fast construction due to their long curing time. This study presents a new kind of rapid hardeni... In some cases of emergency backfill engineering projects, traditional backfill materials cannot meet the requirements of fast construction due to their long curing time. This study presents a new kind of rapid hardening controlled low strength material, which utilizes both rapid hardening sulphoaluminate cement and recycled fine aggregate from urban red brick construction waste. Totally, sixteen mixtures were prepared for the experiment with different cement-to-sand ratios and water-to-solid ratios. The flowability and bleeding rate of fresh mixture were measured to evaluate its workability, and the compressive strength of hardened mixture was tested to evaluate its rapid hardening and mechanical properties. Test results indicate that rapid hardening controlled low strength material containing recycled fine aggregate from urban red brick construction waste can achieve the desirable flowability, but the bleeding rate increases with the increase of flowability. In addition, 2-hour compressive strength can reach 0.08 - 0.12 MPa, and 4-hour compressive strength is 0.32 - 1.54 MPa, which can meet the requirements of emergency backfill construction. At last, based on the derived compressive strength, a fitting model for predicting compressive strength evolution of this new rapid hardening backfill material is developed, which fits accurately with these experimental data. 展开更多
关键词 controlled low STRENGTH MATERIAL Rapid Hardening SULPHOALUMINATE Cement Recycled Fine Aggregate Construction Waste URBAN Red Brick Workability Compressive STRENGTH
下载PDF
Determinant of Low Birth Weight Infants: A Matched Case Control Study 被引量:3
5
作者 Rosnah Sutan Mazlina Mohtar +1 位作者 Aimi Nazri Mahat Azmi Mohd Tamil 《Open Journal of Preventive Medicine》 2014年第3期91-99,共9页
Background: Low birth weight (LBW) is a well-known factor associated with neonatal mortality and has contributed to a range of poor health outcomes. Thus, the objective of this study was to determine factors associate... Background: Low birth weight (LBW) is a well-known factor associated with neonatal mortality and has contributed to a range of poor health outcomes. Thus, the objective of this study was to determine factors associated with LBW infants. Methods: A matched case control study was conducted in Universiti Kebangsaan Malaysia. Data of deliveries were obtained from Total Hospital Information System and medical records. All registered deliveries from January to June 2012 were used as sample populations. There were 180 pairs of cases and controls matched on babies’ gender. Fourteen variables were analyzed: maternal age, ethnicity, gravida, parity, gestational age, maternal booking weight, height and body mass index (BMI), history of low birth weight infants, birth interval, booking hemoglobin levels, hypertension, diabetes mellitus and mode of delivery. Results: Younger mother (t = 6.947, p < 0.001), lower booking BMI (t = 3.067, p = 0.002), prematurity (t = 12.324, p < 0.001), history of LBW infants (OR = 3.0, p = 0.001), LSCS (OR = 0.06, p = 0.001) and current hypertension (OR = 3.1, p = 0.008) were found significant in bivariate analysis. Multivariable conditional logistic regression identified younger maternal age (AOR = 2.9, 95% CI = 1.86 -4.51, p 13.58, p = 0.045), prematurity (AOR = 2.4, 95% CI = 1.79 -3.26, p < 0.001), and current hypertension (AOR = 4.5, 95% CI = 1.06 -19.22, p = 0.041) as significant factors associated with LBW infants. Conclusion: Younger maternal age, history of LBW infants, prematurity and hypertension have been recognized as predictors of LBW infants. The importance of pre-pregnancy screening, early antenatal booking and proper identification of high risk-mother needs to be strengthened and enforced in effort to reduce incidence of LBW infants. 展开更多
关键词 low BIRTH WEIGHT MATERNAL FACTORS Matched CASE control
下载PDF
GROUP VELOCITY CONTROL SCHEME WITH LOW DISSIPATION 被引量:3
6
作者 程军波 傅德薰 马延文 《Chinese Journal of Aeronautics》 SCIE EI CSCD 2000年第3期138-145,共8页
In order to prevent smearing the discontinuity, a modified term is added to the third order Upwind Compact Difference scheme to lower the dissipation error. Moreover, the dispersion error is controled to hold back the... In order to prevent smearing the discontinuity, a modified term is added to the third order Upwind Compact Difference scheme to lower the dissipation error. Moreover, the dispersion error is controled to hold back the non physical oscillation by means of the group velocity control. The scheme is used to simulate the interactions of shock density stratified interface and the disturbed interface developing to vortex rollers. Numerical results are satisfactory. 展开更多
关键词 low dissipation error group velocity control upwind compact difference scheme interactions of shock density stratified interface
下载PDF
DESIGN AND ANALYSIS OF NOVEL ACTIVE ACTUATOR TO CONTROL LOW FREQUENCY VIBRATIONS OF SHAFT SYSTEM 被引量:1
7
作者 YU Yilong LIU Changwen +2 位作者 YANG Yanxiang WANG Shuang ZHANG Junhong 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2008年第6期41-47,共7页
Aiming at providing with high-load capability in active vibration control of large-scale rotor system, a new type of active actuator to simultaneously reduce the dangers of low frequency flexural and torsional vibrati... Aiming at providing with high-load capability in active vibration control of large-scale rotor system, a new type of active actuator to simultaneously reduce the dangers of low frequency flexural and torsional vibrations is designed. The actuator employs electro-hydraulic system and can provide a high and circumferential load. To initialize new research, the characteristics of various kinds of active actuators to control rotor shaft vibration are briefly introduced. The purpose of this paper is to introduce the preliminary results via presenting the structure, functions and operating principles, in particular, the working process of the electro-hydraulic system of the new actuator which includes a set of high speed electromagnetic valves and a series of sloping cone-shaped openings, and presenting the transmission relationships among the control parameters from control signals into the valves to active load onto shaft. The course of the work is dynamic, and a series of spatial forces and moments are put on the shaft to get an external resultant force to reduce excitations that induce vibration of shafts. By checking states of vibration, the actuator can control the impulse width and the interval of injection time for applying different control force to a vibration shaft in two circumference directions through the regulating action of a set of combination directional control valves. The results from simulating analysis and experiment show evidence of that this design can satisfy the case of active process of decreasing of flexural and torsional vibrations. 展开更多
关键词 Actuators low frequency vibration Active control Large-scale rotation shafts System development
下载PDF
Pressurization control system for low pressure crucible casting 被引量:2
8
作者 Li Qiang Hao Qitang Jie Wanqi 《China Foundry》 SCIE CAS 2011年第4期376-379,共4页
A new compact pressurization control system of the low pressure casting machine for crucible pressure casting has been developed. It is especially designed for the production of high-quality aluminum or magnesium allo... A new compact pressurization control system of the low pressure casting machine for crucible pressure casting has been developed. It is especially designed for the production of high-quality aluminum or magnesium alloy parts with low input cost. This machine with such a system has the virtue of economical and compact, and combines the Fuzzy-PID technology and achieves accuracies of ±2.5 mbar. At present, this machine has been adopted by several users in China for the production of aluminum alloy castings with high property requirements. Furthermore, for magnesium alloy castings, this machine can be used with the gas protect unit. 展开更多
关键词 crucible pressure casting low pressure casting pressurization control system
下载PDF
Low Crosstalk Three-Color Infrared Detector by Controlling the Minority Carriers Type of InAs/GaSb Superlattices for Middle-Long and Very-Long Wavelength 被引量:5
9
作者 蒋洞微 向伟 +7 位作者 国凤云 郝宏玥 韩玺 李晓超 王国伟 徐应强 于清江 牛智川 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第4期151-154,共4页
We report a type-Ⅱ InAs/GaSb superlattice three-color infrared detector for mid-wave (MW), long-wave (LW), and very long-wave (VLW) detections. The detector structure consists of three contacts of NIPIN archite... We report a type-Ⅱ InAs/GaSb superlattice three-color infrared detector for mid-wave (MW), long-wave (LW), and very long-wave (VLW) detections. The detector structure consists of three contacts of NIPIN architecture for MW and LW detections, and hetero-junction NIP architecture for VLW detection. It is found that the spectral crosstalks can be significantly reduced by controlling the minority carriers transport via doping beryllium in the two active regions of NIPIN section. The crosstalk detection at MW, LW, and VLW signals are achieved by selecting the bias voltages on the device. At 77K, the cutoff wavelengths of the three-color detection are 5.3μm (at OmV), 141μm (at 300mV) and 19μm (at -20mV) with the detectivities of 4.6xlO11 cm.Hzl/ZW-1, 2.3×10^10 cm.Hzl/2W-1, and 1.0×10^10cm.Hzl/2W-1 for MW, LW and VLW. The crosstalks of the MW channel, LW channel, and VLW channel are almost 0, 0.25, and 0.6, respectively. 展开更多
关键词 GaSb on of low Crosstalk Three-Color Infrared Detector by controlling the Minority Carriers Type of InAs/GaSb Superlattices for Middle-Long and Very-Long Wavelength by InAs for LONG
下载PDF
Unmanned Aerial Vehicle Control of Major Sugarcane Diseases and Pests in Low Latitude Plateau 被引量:1
10
作者 Xiaoyan WANG Rongyue ZHANG +8 位作者 Hongli SHAN Yuanhong FAN Hong XU Pizhong HUANG Zejuan LI Tingying DUAN Ning KANG Wenfeng LI Yingkun HUANG 《Agricultural Biotechnology》 CAS 2019年第4期48-51,共4页
This research was aimed at the defects in traditional artificial spraying control method and the problems such as the difficulty in pesticides applying,labor shortage and low operating efficiency in the middle and lat... This research was aimed at the defects in traditional artificial spraying control method and the problems such as the difficulty in pesticides applying,labor shortage and low operating efficiency in the middle and late stage of sugarcane high stalk crops.The aerial pesticide application technology for sugarcane main diseases and pests was systematically developed and demonstrated from the aspects of aircraft type choice,selection of special pesticides and auxiliaries,integration of pesticides and equipment,field operation,technical specifications,and large-scale application organization mode.The UAV model and flight technical parameters suitable for the sugarcane planting area in low-latitude plateau were analyzed,and the optimal agent formulation combination and application technology of the UAV flight control were screened out,and the UAV flight control was applied to the major sugarcane pests and diseases control in the low-latitude plateau in large scale(UAV flight control was popularized and applied to 15 527 hm 2 in 2018).The research results provided mature whole-process technical support for the normalization of the application of the UVA flight control of major sugarcane pests and diseases.The UAV control technology for major sugarcane pests and diseases had the advantages of ultra-low pesticides applying dosage and high operating efficiency,and could effectively solve the problems such as the difficulty in pesticides applying,labor shortage and low operating efficiency in the middle late growth stage of high stalk crops.This technology successfully opened up a simple,efficient and new way for the effective control of major sugarcane pests and diseases,and practically accelerated the process of integrated control and prevention of sugarcane pests and diseases.In addition,this technology had an extremely significant effect on reducing the loss of sugarcane farmers and enterprises caused by the epidemic and outbreak of sugarcane pests and diseases,increasing sugarcane yield and sugar content.At the same time,this technology played an important role in realizing the whole-process precise control of sugarcane pests and diseases,improving the quality and increasing the efficiency of sugarcane,and guaranteeing the national sugar safety. 展开更多
关键词 low LATITUDE PLATEAU SUGARCANE DISEASES and PESTS Unmanned AERIAL vehicle Prevention and control technology
下载PDF
Numerical Simulation of Stall Flow Control Using a DBD Plasma Actuator in Pulse Mode 被引量:1
11
作者 R.KHOSHKHOO A.JAHANGIRIAN 《Plasma Science and Technology》 SCIE EI CAS CSCD 2016年第9期933-942,共10页
A numerical simulation method is employed to investigate the effects of the unsteady plasma body force over the stalled NACA 0015 airfoil at low Reynolds number flow conditions. The plasma body force created by a diel... A numerical simulation method is employed to investigate the effects of the unsteady plasma body force over the stalled NACA 0015 airfoil at low Reynolds number flow conditions. The plasma body force created by a dielectric barrier discharge actuator is modeled with a phenomenological method for plasma simulation coupled with the compressible Navier-Stokes equations. The governing equations are solved using an efficient implicit finitevolume method. The responses of the separated flow field to the effects of an unsteady body force in various inter- pulses and duty cycles as well as different locations and magnitudes are studied. It is shown that the duty cycle and inter-pulse are key parameters for flow separation control. Additionally, it is concluded that the body force is able to attach the flow and can affect boundary layer grow that Mach number 0.1 and Reynolds number of 45000. 展开更多
关键词 flow control pulse plasma actuation unsteady flow low Reynolds number numerical simulation
下载PDF
1.0 V low voltage CMOS mixer based on voltage control load technique 被引量:1
12
作者 韦保林 戴宇杰 +1 位作者 张小兴 吕英杰 《Journal of Central South University》 SCIE EI CAS 2011年第5期1572-1578,共7页
A CMOS active mixer based on voltage control load technique which can operate at 1.0 V supply voltage was proposed, and its operation principle, noise and linearity analysis were also presented. Contrary to the conven... A CMOS active mixer based on voltage control load technique which can operate at 1.0 V supply voltage was proposed, and its operation principle, noise and linearity analysis were also presented. Contrary to the conventional Gilbert-type mixer which is based on RF current-commutating, the load impedance in this proposed mixer is controlled by the LO signal, and it has only two stacked transistors at each branch which is suitable for low voltage applications. The mixer was designed and fabricated in 0.18 tam CMOS process for 2.4 GHz ISM band applications. With an input of 2.44 GHz RF signal and 2.442 GHz LO signal, the measurement specifications of the proposed mixer are: the conversion gain (Gc) is 5.3 dB, the input-referred third-order intercept point (PIIP3) is 4.6 dBm, the input-referred 1 dB compression point (P1dB) is --7.4 dBm, and the single-sideband noise figure (NFSSB) is 21.7 dB. 展开更多
关键词 CMOS active mixer voltage control load technique low voltage
下载PDF
Low energy consumption depth control method of self-sustaining intelligent buoy 被引量:1
13
作者 ZHENG Di XU Jiayi +1 位作者 LI Xingfei LI Hongyu 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2021年第1期74-82,共9页
Aiming at the contradiction between the depth control accuracy and the energy consumption of the self-sustaining intelligent buoy,a low energy consumption depth control method based on historical array for real-time g... Aiming at the contradiction between the depth control accuracy and the energy consumption of the self-sustaining intelligent buoy,a low energy consumption depth control method based on historical array for real-time geostrophic oceanography(Argo)data is proposed.As known from the buoy kinematic model,the volume of the external oil sac only depends on the density and temperature of seawater at hovering depth.Hence,we use historical Argo data to extract the fitting curves of density and temperature,and obtain the relationship between the hovering depth and the volume of the external oil sac.Genetic algorithm is used to carry out the optimal energy consumption motion planning for the depth control process,and the specific motion strategy of depth control process is obtained.Compared with dual closed-loop fuzzy PID control method and radial basis function(RBF)-PID method,the proposed method reduces energy consumption to 1/50 with the same accuracy.Finally,a hardware-in-the-loop simulation system was used to verify this method.When the error caused by fitting curves is not considered,the average error is 2.62 m,the energy consumption is 3.214×10^(4)J,and the error of energy consumption is only 0.65%.It shows the effectiveness and reliability of the method as well as the advantages of comprehensively considering the accuracy and energy consumption. 展开更多
关键词 self-sustaining intelligent buoy low energy consumption depth control Argo data genetic algorithm hardware-in-the-loop simulation system
下载PDF
Safer Design and Less Cost Operation for Low-Traffic Long-Road Illumination Using Control System Based on Pattern Recognition Technique 被引量:1
14
作者 Muhammad M. A. S. Mahmoud Leyla Muradkhanli 《Intelligent Control and Automation》 2020年第3期47-62,共16页
The paper covers analysis and investigation of lighting automation system in low-traffic long-roads. The main objective is to provide optimal solution between expensive safe design that utilizes continuous street ligh... The paper covers analysis and investigation of lighting automation system in low-traffic long-roads. The main objective is to provide optimal solution between expensive safe design that utilizes continuous street lighting system at night for the entire road, or inexpensive design that sacrifices the safety, relying on using vehicles lighting, to eliminate the problem of high cost energy consumption during the night operation of the road. By taking into account both of these factors, smart lighting automation system is proposed using Pattern Recognition Technique applied on vehicle number-plates. In this proposal, the road is sectionalized into zones, and based on smart Pattern Recognition Technique, the control system of the road lighting illuminates only the zone that the vehicles pass through. Economic analysis is provided in this paper to support the value of using this design of lighting control system. 展开更多
关键词 Road Lighting control Road Lighting Automation Vehicle Number-Plate Pattern Recognition Smart Grid Power Management low Traffic Roads Image Processing
下载PDF
Assessment of Stress Cognitive Control and Executive Function with Stress Control Rating Scale (ECOSTRESS) and Low Resolution Brain Electromagnetic Tomography (LORETA) (In Portuguese People in Situations of Unemployment and Economic Insufficiency) 被引量:1
15
作者 Eduardo Gonçalves Marco Moniz Saul Neves Jesus 《Open Journal of Psychiatry》 2016年第2期158-164,共7页
This article reviews the constructs of stress, appraisal, coping, according to a transactional perspective, and executive function, and presents a stress control rating scale (ECOSTRESS), which design is founded in th... This article reviews the constructs of stress, appraisal, coping, according to a transactional perspective, and executive function, and presents a stress control rating scale (ECOSTRESS), which design is founded in these constructs. This psychometric tool is useful in the assessment of cognitive control of stress, correlated with the function of dorsolateral prefrontal cortex. It has been validated for its use in the assessment of Portuguese people in situations of stress related to unemployment and economic insufficiency. Also, within the context of the cognitive control of stress, it is highlighted the usefulness of low resolution brain electromagnetic tomography (LORETA). 展开更多
关键词 Stress Anxiety Depression MANIA Economic Insufficiency Executive Function Anterior Cingulate Cortex Dorsolateral Prefrontal Cortex Stress control Rating Scale (ECOSTRESS) low Resolution Brain Electromagnetic Tomography (LORETA) NEUROFEEDBACK
下载PDF
Risk Factors of Low Back Pain among the Chinese Occupational Population:A Case-control Study 被引量:7
16
作者 LI Jing Yun WANG Sheng +6 位作者 HE Li Hua WU Shan Shan YANG Lei YU Shan Fa LI Li Ping WANG Jian Xin HUANG Yan Di 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2012年第4期421-429,共9页
Objective To explore the risk factors of low back pain among the Chinese occupational population in several major industries. Methods A total of 7200 subjects (3600 cases and 3600 controls) were randomly sampled fro... Objective To explore the risk factors of low back pain among the Chinese occupational population in several major industries. Methods A total of 7200 subjects (3600 cases and 3600 controls) were randomly sampled from a cross-sectional study, and they were investigated for individual and occupational factors of low back pain. The potential risk factors were first selected by using chi-square tests. Secondly, collinearity diagnosis proceeded by using the Kendall's rank correlation. Finally, binary logistic regression model was used for multi-factor analysis. Results Collinearity diagnosis showed that there was a severe collinearity problem among the potential risk factors of low back pain. Logistic regression model included 20 variables with statistical significance. Bending neck forward or holding neck in a forward posturefor long periods (0R=1.408) was the most important risk factor inducing low back pain in this study, followed by bending heavily with the trunk (0R=1.402), carrying out identical work almost for the whole day (0R=1.340). Additionally, suHicient normal break was a protective factor of low back pain. Conclusion Low back pain among the Chinese occupational population was associated with body height, occupation, work organization, physical work, working posture, and others. All these risk factors could be regarded as the indicators of low back pain, and some relevant preventive measures should be taken to reduce low back pain risk. 展开更多
关键词 Case-control studies low back pain Occupational health Risk factors
下载PDF
Integration and Application of Comprehensive Prevention and Control Technology for Sugarcane Borers in Low Latitude Plateau of China
17
作者 Wenfeng LI Rongyue ZHANG +6 位作者 Jiong YIN Xiaoyan WANG Hongli SHAN Jie LI Zhiming LUO Xiaoyan CANG Yingkun HUANG 《Agricultural Biotechnology》 CAS 2019年第4期72-77,80,共7页
Aimed at the difficult problem of prevention and control of disastrous sugarcane borers in low latitude plateau of China,this research systematically overcame the bottleneck of comprehensive prevention and control of ... Aimed at the difficult problem of prevention and control of disastrous sugarcane borers in low latitude plateau of China,this research systematically overcame the bottleneck of comprehensive prevention and control of sugarcane bores after 10 years of collaborative research,and formed a number of core product technologies,which promoted the green and high-quality development of the sugarcane industry and achieved the following innovative results.In this study,the species,population structure and damage characteristics of disastrous sugarcane borers in low latitude plateau were clarified for the first time,which provided a scientific basis for the formulation of technology and application of comprehensive prevention and control.The monitoring technology system and early warning monitoring network were constructed for the monitoring of borer population in low latitude plateau sugarcane area,which realized the accurate monitoring of the population dynamics of sugarcane bores and provided technical support for comprehensive prevention and control.The flight spraying technology by unmanned aerial vehicle(UAV)was developed for bores in the low latitude plateau cane area,and it has been successfully applied in a large area,thereby opening up a new way of light,simple and efficient for effective control of borers.The scale application of lamp trapping and sexual attracting to kill adult insects technology promoted the advancement of green control technology of bores.Integration was made to the comprehensive control techniques like UAV flight control,biological agents,physical and chemical inducement and control,and sexual attractant trapping in the low latitude plateau sugarcane area,and standardized technical regulations have been formulated,which significantly improved the overall prevention and control effect of large areas.The technologies for the comprehensive prevention and control of sugarcane borers have been popularized and applied in 8 major sugarcane producing states(cities)in low altitude plateau of Yunnan over the years,which has controlled the damage and showed remarkable control effect.In 2017-2018,the integrated control technology was popularized and applied to a total of 2.78×10^5 hm^2(1.33×10^4 hm^2 of UAV flight control)of area,which recovered a total of 3.666×10^6 t of sugarcane losses,increasing 4.69×10^5 t of sugar with the sales increase of 3.979 billion yuan,added profits of 1.251 billion yuan and the taxes increase of 188 million yuan.The research results show that the technology has high technical integration,strong practicability,high degree of transformation,significant economic,social and ecological benefits,which provide technical supports for the sustainable development,loss reduction and efficiency increase of the sugarcane industry in the low-latitude plateau sugarcane region,and make significant contributions to the economic development of ethnic minorities in the border-stricken areas and the increase of farmers income and poverty alleviation. 展开更多
关键词 low LATITUDE PLATEAU SUGARCANE BORERS COMPREHENSIVE PREVENTION and control Application
下载PDF
An Advance Commutation Control Method for Low Torque Ripple of Brushless DC Motors 被引量:6
18
作者 SHI Jian Li Tiecai 《中国电机工程学报》 EI CSCD 北大核心 2012年第30期I0016-I0016,18,共1页
该文给出一种优化的无刷直流电动机变母线电压六拍控制方法。既解决了传统六拍控制策略中由于绕组电感所造成的电流滞后问题,又改善了由于换相所造成的电流脉动问题。该方法是通过在每两拍之间插入一小段缓冲区来实现的,该缓冲区使下一... 该文给出一种优化的无刷直流电动机变母线电压六拍控制方法。既解决了传统六拍控制策略中由于绕组电感所造成的电流滞后问题,又改善了由于换相所造成的电流脉动问题。该方法是通过在每两拍之间插入一小段缓冲区来实现的,该缓冲区使下一拍将要切入的电流提前切入,同时使当前拍将要切出的电流延迟切出。通过确定缓冲区的起始位置,即超前换相角的大小,保证每一拍所对应的相电流的中心和反电动势的中心重合。通过选取缓冲区开关器件PWM调制的占空比,降低电机运行过程中的换相转矩脉动。该文方法只需根据负载大小选取超前换相角,一旦选定适用于所有转速。文中给出了该方法的理论推导过程和实验验证波形,从实验结果可以发现,电流滞后被消除,换相电流脉动显著减小,电机的利用率得到提高。 展开更多
关键词 换相转矩脉动 换相控制 无刷直流电机 无刷直流电动机 直流母线电压 BLDCM 绕组电感 相电流
下载PDF
Dynamic Monitoring and Control Measures of Spodoptera frugiperda(J.E.Smmith) in Low Latitude Plateau Sugarcane Areas
19
作者 Xiaoyan CANG Rongyue ZHANG +5 位作者 Jiong YIN Hongli SHAN Jie LI Xiaoyan WANG Zhiming LUO Yinkun HUANG 《Agricultural Biotechnology》 CAS 2019年第5期70-72,75,共4页
Spodoptera frugiperda (J.E.Smmith) is one of the major migratory pests warned by the Food and Agriculture Organization (FAO).It has been successfully invaded sugarcane and corn in Jinggu,Longchuan,Gengma,Menghai,Yingj... Spodoptera frugiperda (J.E.Smmith) is one of the major migratory pests warned by the Food and Agriculture Organization (FAO).It has been successfully invaded sugarcane and corn in Jinggu,Longchuan,Gengma,Menghai,Yingjiang,Lancang of Yunan Province,China.In view of the great variety of hosts,wide range of habitats and strong migration ability,S.frugiperda has the potential of causing catastrophic threats to sugarcane production.In this paper,we made a systematic introduction to the morphological and biological characteristics of S.frugiperda,analyzed its occurrence situations and occurrence trends in Yunnan of China and other countries around the world,and proposed the control strategies and measures of ecological regulation and control,natural enemies protection and utilization,biological control,pesticide control and adults trapping based on the outbreak characteristics of S.frugiperda and the actual sugarcane production in low latitude plateau areas. 展开更多
关键词 low LATITUDE PLATEAU areas SPODOPTERA frugiperda OCCURRENCE Dynamic monitoring Prevention and control measures
下载PDF
A low noise charge sensitive preamplifier with switch control feedback resistance 被引量:3
20
作者 WEMBE TAFO Evariste SU Hong +2 位作者 PENG Yu WU Ming QIAN Yi 《Nuclear Science and Techniques》 SCIE CAS CSCD 2008年第1期39-44,共6页
In this paper, the design and analysis of a new low noise charge sensitive preamplifier for silicon strip, Si(Li), CdZnTe and CsI detectors etc. with switch control feedback resistance were described, the entire syste... In this paper, the design and analysis of a new low noise charge sensitive preamplifier for silicon strip, Si(Li), CdZnTe and CsI detectors etc. with switch control feedback resistance were described, the entire system to be built using the CMOS transistors. The circuit configuration of the CSP proposed in this paper can be adopted to develop CMOS-based Application Specific Integrated Circuit further for Front End Electronics of read-out system of nuclear physics, particle physics and astrophysics research, etc. This work is an implemented design that we succeed after a simulation to obtain a rise time less than 3ns, the output resistance less than 94? and the linearity almost good. 展开更多
关键词 电流放大器 粒子探测技术 开关 反射电阻
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部