疲劳方对改善单纯气虚质镜下血尿人群的疗效观察

目的:观察疲劳方对改善气虚质血尿人群的疗效。方法:选取65岁以上老年体检气虚质血尿人群及门诊气虚质血尿就诊人群,无任何肾脏、泌尿系统疾患的,排除其他因素导致的以及慢性疾病控制稳定的,依从性良好的,完全自理的,自愿接受疲劳方的治疗人群。结果:共随访三次,在第二次随访后,可以证实气虚质血尿人群在使用疲劳方三个月后,改善尿沉渣红细胞计数有显著效果(P=0.013)。结论:气虚质血尿人群在使用疲劳方三个月后,尿沉渣红细胞计数较使用前明显减少,具有统计学意义(P<0.05)。

抗疲劳膏方联合肺康复治疗慢性阻塞性肺疾病临床研究

目的观察抗疲劳膏方联合肺康复疗法治疗慢性阻塞性肺疾病(chronic obstructive pulmonary disease,COPD)的临床疗效。方法采用前瞻性随机对照方法将100例COPD缓解期患者分为2组。治疗组50例,治疗以抗疲劳膏方联合肺康复为主。对照组50例,仅用使用布地格福吸入气雾剂2揿,吸入,每日两次联合注射用头孢哌酮钠舒巴坦钠。疗程2周,随诊3个月,观察治疗前后中医证候量表、COPD评估测试问卷(CAT)等指标变化,并记录抗生素时长,急性发作间期时长。结果经治疗后两组的中医证候评分,CAT评分均较治疗前均有显著降低,且治疗组显著低于对照组。抗生素使用时长治疗组显著低于对照组,治疗组较对照组急性发作人次少且发作间期时长更长。结论两组均可以改善临床症状,但抗疲劳膏方联合肺康复治疗COPD较单纯西药治疗更佳。

New Fatigue Test and Statistical Method for Metallic Materials Used in Vehicle Transmissions

Aim To improve the efficiency of fatigue material tests and relevant statistical treatment of test data. Methods\ Least square approach and other special treatments were used. Results and Conclusion\ The concepts of each phase in fatigue tests and statistical treatment are clarified. The method proposed leads to three important properties. Reduced number of specimens brings to the advantage of lowering test expenditures. The whole test procedure has more flexibility for there is no need to conduct many tests at the same stress level as in traditional cases.

Evaluation of fatigue property of asphalt mixtures based on digital image correlation method

In order to evaluate the accumulative of tensile strain in the process of fatigue failure, the digital image correlation（DIC） method was utilized to characterize the tensile strain development of asphalt mixtures in the indirect tensile（IDT）fatigue test. Three typical hot mix asphalt（HMA） mixtures with varying nominal maximum aggregate sizes were tested at four stress levels. During the tests, a digital camera was mounted to capture the displacement/strain fields on the surface of the specimen by recording the real-time change of speckle position. The results indicate that the vertical deformation curve can barely evaluate the fatigue performance accurately due to the non-negligible local deflection near the loading point. However, based on the analysis of strain fields,the optimal fatigue cracking zone is determined as a 40mm×40mm rectangle in the middle of the specimens. Also, a reasonable fatigue model based on the tensile strain curves calculated by DIC is proposed to predict the fatigue lives of asphalt mixtures.

Normalization method for asphalt mixture fatigue equation under different loading frequencies

In order to analyze the effect of different loading frequencies on the fatigue performance for asphalt mixture,the changing law of asphalt mixture strengths with loading speed was revealed by strength tests under different loading speeds.Fatigue equations of asphalt mixtures based on the nominal stress ratio and real stress ratio were established using fatigue tests under different loading frequencies.It was revealed that the strength of the asphalt mixture is affected by the loading speed greatly.It was also discovered that the fatigue equation based on the nominal stress ratio will change with the change of the fatigue loading speed.There is no uniqueness.But the fatigue equation based on the real stress ratio doesn't change with the loading frequency.It has the uniqueness.The results indicate the fatigue equation based on the real stress ratio can realize the normalization of the asphalt mixture fatigue equation under different loading frequencies.It can greatly benefit the analysis of the fatigue characteristics under different vehicle speeds for asphalt pavement.

The effect of shoe type on gait in forefoot strike runners during a 50-km run

Purpose:To observe the relative change in foot-strike pattern,pressure characteristics,surface electromyography(sEMG) recordings,and stride characteristics in forefoot strike runners wearing both minimalist and traditional shoes during a 50-km run.Methods:Four experienced minimalist runners were enrolled in this study.Each runner ran a 50-km simulated run in both minimalist shoes and traditional shoes.Pressure data,sEMG recordings,and limited 3D motion capture data were collected during the initial 0.8 km and final 0.8 km for each trial.Results:Three runners in the traditional shoe type condition and one runner in the minimalist shoe type condition demonstrated a more posterior initial contact area(midfoot strike(MFS) pattern) after the 50-km run.which was supported by increased activity of the tibialis anterior in the pre-contaet phase(as per root mean square(RMS) values).In addition,in both pre- and post-run conditions,there were increased peak pressures in the minimalist shoe type,specifically in the medial forefoot.Muscle fatigue as defined by a decreased median frequency observed in isometric,constant force contractions did not correspond with our hypothesis in relation to the observed foot strike change pattern.Finally,step rate increased and step length decreased after the 50-km run in both shoe type conditions.Conclusion:More runners adopted a more posterior initial contact area after the 50-km run in the traditional shoe type than in the minimalist shoe type.The runners who adopted a more posterior initial contact area were more closely associated with an increased median frequency of the medial gastrocnemius,which suggests there may be a change in motor unit recruitment pattern during long-distance,sustained velocity running.The increased peak pressures observed in the medial forefoot in the minimalist shoe type may predispose to metatarsal stress fractures in the setting of improper training.

Study of vehicle accident reconstruction based on the information of the tire marks

The tire mark is the important legacy information left at the accident scene. Based on the vehicle collision dynamics model, this study provided an optimized algorithm with vehicle final location and other related information for the tire marks. When the tire marks simulation results fit the real one well, the state of vehicle can be understood as the real state in the accident. Based on above, the vehicle velocity and direction are decided. According to the velocity and direction of the vehicle, the complete accident process can be simulated. With the help of the Pc-Crash software, the method has been applied in typical collision accident cases analysis. The reconstruction results will provide the scientific and numerical references for vehicle collision accidents analyzing and appraising.

Failure analysis study of railway draw-hook coupler

Failure analysis of railway draw-hook coupler was carried out.The nondestructive testing method was undertaken on some failed couplers in service to designate critical areas of a coupler.Draw-Hook coupler is used to connect with the same hook coupler or automatic coupler.The influence of each connection types on the coupler strength in this study was discussed.A numerical stress analysis using FEM was performed,and many approaches including critical plane approach were carried out on fatigue life prediction of coupler under different conditions.The results of the proposed fatigue criterion and fatigue life predictions,as well as static numerical analysis,are validated with experimental results.

Statistical Analysis Methods of Fatigue Crack Growth Rate

The standard center-cracked tensile specimens M （T） with different widths made of aluminum alloy were designed for fatigue crack growth rate experiments, and the effect of specimen size on the fatigue crack growth rate was discussed. The firing equation and the p-da/dN-△K curve of fatigue crack growth rate （with different confidence and reliability levels） were obtained by one-side tolerance factor analysis. In order to reasonably reflect the dispersion of material properties on the fatigue crack growth rate and fatigue crack propagation life, two novel statistical analysis methods were proposed, which can be used to describe the probability distribution of fatigue crack growth rate. Compared with the traditional statistical analysis method of probabilistic fatigue crack growth rate, the fitted curves from the novel statistical analysis methods yield more objective description on the probability distribution of crack growth rate.

BUCKLING OF SPATIAL CURVED RODS WITH CIRCULAR CROSS-SECTIONS

Formulae for determining Green strain of an initially curved and twisted rod with circular cross-sections are derived by using the natural (curvilinear) coordinate system. Finite element analyses are performed for the flexural buckling of initially curved and twisted thin rods under simultaneous action of axial force and torque. Numerical examples demonstrate that the given formulae are correcte. Some numerical results are compared with existing analytical solutions and data obtained by commercial FE software. The convergence of the proposed curved element is better than that of elements in the commercial FE software. It is shown that good accuracy and convergency are achieved by solving three-dimensional problems.

Statistical Analysis for the Birnbaum-Saunders Fatigue Life Distribution under Multiply Type-ⅡCensoring

In present paper, we derive the quasi-least squares estimation(QLSE) and approximate maximum likelihood estimation(AMLE) for the Birnbaum-Saunders fatigue life distribution under multiply Type-Ⅱcensoring. Furthermore, we get the variance and covariance of the approximate maximum likelihood estimation.

The Stress Combination Method for the Fatigue Assessment of the Hatch Corner of a Bulk Carrier Based on Equivalent Waves

The stress combination method for the fatigue assessment of the hatch comer of a bulk carrier was investigated based on equivalent waves. The principles of the equivalent waves of ship structures were given, including the determination of the dominant load parameter, heading, frequency, and amplitude of the equivalent regular waves. The dominant load parameters of the hatch comer of a bulk carrier were identified by the structural stress response analysis, and then a series of equivalent regular waves were defined based on these parameters. A combination method of the structural stress ranges under the different equivalent waves was developed for the fatigue analysis. The combination factors were obtained by least square regression analysis with the stress ranges derived from spectral fatigue analysis as the target value. The proposed method was applied to the hatch comer of another bulk carrier as an example. This shows that the results from the equivalent wave approach agree well with those from the spectral fatigue analysis. The workload is reduced substantially. This method can be referenced in the fatigue assessment of the hatch comer of a bulk carrier.

New extrusion process of Mg alloy automobile wheels

The recent research and development of forged magnesium road wheel were reviewed.Methods of flow-forming,spin forging of manufacturing a forged magnesium alloy wheel were introduced.A new extrusion method was investigated especially. Extrusion from hollow billet was proposed in order to enhance the strength of spoke portion and reduce the maximum forming load. By means of the developed technique,the one-piece Mg wheels were produced successfully by extrusion from AZ80+alloy.At the same time,the existing problems on the research and development of forged magnesium road wheel were analyzed.The impact testing,radial fatigue testing and bending fatigue testing results show that AZ80+wheel can meet application requirement in automobile industry.

Recovery Methods for Athletes＇ Intensive Training and Competition Fatigue

After athletes＇ intensive training and competition, they would suffer from fatigue. Therefore, the measures to recover their motor and nervous systems from the fatigue are very important. In this research, this author tries to investigate the methods to recover one＇ s joints and relax one＇ s nervous system, and detailed methods would also be provided for reference. Objective conditions, like sports fields and equipment, have become relatively satisfactory. There are high-level coaches and athletes who are carefully and scientifically chosen, so that good athletic performance is well guaranteed. To improve sports teams＇ comprehensive sports skills, we have to adopt and grasp some advanced training methods and skills. But after intensive training and fierce competition, athletes＇ motor and nervous system would suffer from fatigue, therefore, it becomes necessary for them to grasp the methods of recovery. In this research, this author tries to investigate the mechanism and methods to recover athletes＇ joints from the fatigue and relax their nervous system.

A generalized plane strain theory for transversely isotropic piezoelectric plates

Study of generalized plane strain has so far been limited to elasticity. The present is aimed at parallel development of transversely isotropic piezoelasticity. By assuming that the along depth distribution of electric potential is linear, and that com- monly used Kane-Mindlin kinematical assumption is valid, two dimensional solution systems were deduced, for which, explicit solutions of the out-of-plane constraint factor, as well as the stress resultant concentration factor around a circular hole in a transversely isotropic piezoelectric plate subjected to remote biaxial tension are obtained. Comparisons of these formulas with their counterparts for elastic case yielded suggestions that whether the piezoelectric effect exacerbates or mitigates the stress resultant concentration greatly depends on material properties, particularly, the piezoelectric coefficients; the effect of plate thickness was extensively investigated.

Hardness-Based Non-destructive Method for Developing Location Specific S-N Curves for Fatigue Life Evaluation

This paper first describes the importance of using location specific S-N curves for fatigue damage assessment of existing steel structures. It discusses the existing concepts and methods for developing S-N curves using empirical formulae and monotonic strength parameters, such as the ultimate tensile strength and hardness. It also discusses relationships among these monotonic parameters. Then it presents formulae for developing hardness-based full range S-N curves for medium strength steels. The formulae are verified using experimental data obtained from both monotonic and cyclic testing. Finally, it describes the advantages of these hardness-based formulae for developing location specific S-N curves as hardness testing is a non-destructive test which can be carried out on specific locations in structures.

Reducing the Effects of Driving Fatigue with Magnetic Stimulation

The purpose of this study was to assess the effects of reducing driving fatigue with magnitopuncture stimuli on Dazhui (DU14) point and Neiguan (PC6) points using heart rate (HR), reaction time (RT) testing, critical flicker fusion frequency (CFF) and subjective evaluation. Twenty healthy subjects were randomly divided into two groups: A-group (study group) and B-group (control group). All subjects were required to be well rested before the experiment. The subjects were engaged in high speed driving at a constant vehicle velocity of 80 km/h continuously for three hours on a test course simulating an expressway. During the driving magnitopunctures were applied to the Dazhui (DU14) point and Neiguan (PC6) points for the A-group when the subject performed the task for two and half hours, and for the B-group magnitopunctures were applied to non-acupuncture points at the same time session. In this study RT exbited a significant delay in B-group (P<0.01) but no found in A-group after the driving task. CFF and subjective evaluation also exhibited significant differences between the two groups after the driving task (P<0.05). The findings showed that magnitopuncture stimuli on Dazhui (DU14) point and Neiguan (PC6) points could reduce the effects of driving fatigue.

An intelligent method for contact fatigue reliability analysis of spur gear under EHL

To complete the contact fatigue reliability analysis of spur gear under elastohydrodynamic lubrication(EHL) efficiently and accurately, an intelligent method is proposed. Oil film pressure is approximated using quadratic polynomial with intercrossing term and then mapped into the Hertz contact zone. Considering the randomness of the EHL, material properties and fatigue strength correction factors, the probabilistic reliability analysis model is established using artificial neural network(ANN). Genetic algorithm(GA) is employed to search the minimum reliability index and the design point by introducing an adjusting factor in penalty function. Reliability sensitivity analysis is completed based on the advanced first order second moment(AFOSM). Numerical example shows that the established probabilistic reliability analysis model could correctly reflect the effect of EHL on contact fatigue of spur gear, and the proposed intelligent method has an excellent global search capability as well as a highly efficient computing performance compared with the traditional Monte Carlo method(MCM).

A Proposal of Deciding Fatigue Strength in Bending Fatigue Test

Generally, the fatigue crack is initiated and then it is propagated toward the welding direction and the thickness direction. Finally, the joints lose the resistance to the external force. At present, as there is no deciding method of the fatigue strength （fatigue life）, this paper proposed it from the result obtained by bending test for fillet welded joints. Judging initiation of the fatigue crack from the measured value of strain gages, there was a possibility that the fatigue crack occurred at both sides of fillet welded joints. However, this was a different result from that of macrograph of cross section. On the other hand, the results obtained by FSM （field signature method） coincided with the result of macrograph of cross section. For the initial state, potential difference obtained by the electrostatic analysis based on FEM （finite element method） and that by FSM was accurately coincided. After confirming validity of the crack model for analysis, the crack model was specified by reproducing the propagating process of crack accurately through trial and error. It was concluded that the state which could not resist to the external force was regarded as fatigue strength based on equivalent stress obtained by elastic stress analysis for specified crack model. From the experimental result, it was proposed that 90% of repetition number corresponding to the state which could not resist to the external force （at the finish of the test） was regarded as fatigue strength （fatigue life） in consideration of safety and as the first approximation.