体力活动的测量与评价

本研究对体力活动的概念及分类进行系统梳理,主要差别是"基础代谢"是否包含概念之中。体力活动的测量方法既服务于大众体育领域,在临床医学监测和运动处方制定等方面具有重要意义,应针对目标人群或体力活动内容特征进行个性化的行为测量和能量消耗测量。体育、医务、教育工作者应结合国际体力活动量表(IPAQ)和全球体力活动量表(GPAQ),制定适合我国国民的运动处方、体力活动干预和行为习惯改善方法等,找到适合中国特色健康促进政策和有效的实施方法,促进"健康中国梦"的实现。

脊柱手法的力学研究概况

脊柱手法治疗脊柱疾病,国内外很多研究者进行了活体的手法力学测定,本文进行了总结,但由于技术限制,只能测量术者手指掌面的压力,近年来随着计算机仿真技术的发展,脊柱生物力学仿真技术提供了方便、真实度高的技术,可以实时计算关节、椎间盘、肌肉、韧带等脊柱内部的应力应变,结合活体的力学测量系统测量腰部手法操作的力学、运动学变化过程等,为揭示手法治疗脊柱损伤性疾病的机理,分析脊柱手法技术操作特点及影响因素提供了科学量化的方法,并对临床治疗提供了宝贵的基础研究数据。

DPIV系统研制及其应用

笔者在北京航空航天大学流体力学研究所多年从事系统的PIV测试技术研究,经过科研攻关成功研制出目前国内第一套完善的实时数字式粒子图像测速(DigitalParticleImageVelocimetry)系统,实现了速度场和涡量场的实时测量,而且已经成功地应用于各项流体力学的实验测量中,其中包括:1.5M超声速喷流实验、三角翼前缘涡破裂复杂流场测量实验、大型工程水洞流场校测、绕摆动圆柱卡门涡测量实验以及锥阀管道模型和漩涡分离器内部流场测量实验等[1～3]。

导流件和叶轮强作用涡轮流量计的CFD仿真方法

分别采用多重参考坐标系(MRF)方法和滑移网格方法,对导流件和叶轮强作用的涡轮流量计内部流场,进行了计算流体力学(CFD)仿真,并计算了仿真仪表系数。结果表明:采用MRF仿真方法时,仿真模型中导流叶片和叶轮叶片的相对位置对仿真结果有较大影响;采用滑移网格方法对涡轮流量传感器内部流场进行仿真更合理,仿真仪表系数和线性度与实验结果相比更准确。

导航卫星历书参数拟合算法研究

对导航卫星历书问题进行了综合研究,并结合J_2项分析解,提出了两套新的历书参数拟合方法和用户算法,与正常算法不同的是:8参数历书拟合算法以(?)=-3/2J_2等(R_e^2)/(p^2)n cos i隐性直接代替历书参数Ω_1;在用户算法中对MEO卫星以ω_k=ω_0-ω_1·(Δt/2-t_k),对高轨卫星以ω_k=ω_0-ω_1·(Δt/2-t_k)/2修正历书参数ω_k,其中ω_1=(A_2)/(p^2)n(2-5/2sin^2 i).9参数历书拟合算法在8参数的基础上增加了一个历书参数(?)=(T_Err_n-T_Err_0)/Δt/α参数,在用户算法中以ω_k=ω_0-ω_1·(Δt/2-t_k),M_k=M_0+n·t_k-(?)·(Δt/2-t_k)修正ω_k和M_k.通过多组模拟轨道和IGS精密轨道的历书拟合实验,结果表明,新8参数历书拟合方法具有参数少、迭代收敛速度快、对MEO卫星拟合精度高等优点;新9参数历书拟合算法,迭代收敛快,拟合精度优于其他算法.

北斗卫星导航系统服务精度评估

精度是北斗卫星导航系统(Beidou Navigation Satellite System,BDS)服务指标体系的重要内容.给出了北斗卫星导航系统精度指标的含义及精度指标的评估方法,利用实测数据分析了北斗系统实际实现的精度指标,并将其与GPS系统实际实现的精度指标作比较分析.DOP(几何精度因子)值由卫星导航系统空间星座分布决定,是影响用户定位授时精度的重要因素,比较了北斗与GPS在中国区域DOP值分布的差异.GPS系统PDOP(定位几何精度因子)分布均匀,随用户经度和纬度变化不大,在1.0–2.0之间.而受混合星座影响,北斗系统PDOP分布随着测站经度和纬度变化较大,变化范围为1.5–5.0;且随测站纬度增加而变大,由中心经度(东经118?)向两侧不断变大.对于影响用户等效距离误差的空间信号精度进行了比较分析.利用IGS(国际GNSS服务组织)提供的事后精密轨道、激光跟踪数据和北斗双向时频传递测量的卫星钟差评估了北斗基本导航电文的精度.结果表明:北斗IGSO(倾斜地球同步轨道)卫星和MEO(中轨道)卫星轨道径向误差约为0.5 m,大于GPS卫星轨道小于0.2 m的径向误差.北斗GEO(地球同步轨道)卫星激光残差约为65 cm,IGSO卫星和MEO卫星激光残差约为50 cm.受卫星钟差数据龄期影响,MEO卫星钟差参数误差明显大于IGSO卫星和GEO卫星,约为0.80 m.最后,采用MGEX(多GNSS系统试验项目)多模接收机进行了定位试验,分析了北斗系统和GPS在定位精度上的差异.结果表明:受星座构型影响,北斗卫星导航系统定位精度与GPS系统定位精度相比有所差异,但满足水平定位精度优于10 m、高程定位精度优于10 m的设计要求,双系统组合定位精度好于单一系统定位精度.

Experimental Study on Hydrodynamics of L-type Podded Propulsor in Straight-ahead Motion and Off-Design Conditions

Experimental tests were conducted to evaluate the hydrodynamic performance of an L-type podded propulsor in straight-ahead motion and off-design conditions using an open-water measuring instrument developed by the authors for podded propulsors, a ship model towing tank, and under water particle image velocimetry （PIV） measurement systems. Under the three types of conditions, the main parameters of an L-type podded propulsor were measured, including the propeller thrust and torque, as well as the thrust, side force, and moment of the whole pod unit.In addition, the flow field on the section between the propeller and the strut was analyzed. Experimental results demonstrate that the dynamic azimuthing rate and direction and the turning direction affect the forces on the propeller and the whole pod unit. Forces are asymmetrically distributed between the left and right azimuthing directions because of the effect of propeller rotation. The findings of this study provide a foundation for further research on L-type podded propulsors.

Calculation of wave and current loads on launching offshore jacket

It’s very complicated to calculate and analyze the wave and current loads on naval architectures since the sea condition is uncertain and complicated and the determinants vary from different form types and dimensions. For calculating the wave and current loads on upright small-long-size pipe, the Morrison equation is practical and applied. Jacket platform is a kind of offshore space frame structure comprised of lots of poles that are circular cylinders with small diameter and in the oblique status relative to seabed. In this paper, based on Morrison equation, the specific method and procedure calculating the wave and current loads on launching jacket are given and applied on a typical launching jacket. The instance shows that the method and procedure are convenient and make the calculation and analysis in good agreement with actual launching.

PRELIMINARY PROGRAMMED WHOLE-BODY COUNTER

It is capable of giving the initial intakes of radionuclides and the assessment quantities used in radiation protection according to its measured results of radionuclides in vivo. It is accomplished by providing the software of controlling, interface and internal dose estimation programs to the original iron cabin shielding whole-body counter. The preliminary application shows that its data processing is rapid and correct, and can meet the requirement of rapid internal radioactive contamination monitoring and diagnosing in case of lots of internal contamination subjects happened innuclear accident.

Correlates of subjectively and objectively measured physical activity in young adolescents

Background： Many studies examining individual-level correlates in youth utilize self-report rather than objective measures of physical activity （PA）. This utilization of self-report may result in associations that are not present when examining objectively measured PA. The present study investigates the relationship between hypothesized correlates of PA with objectively and subjectively measured PA. Methods： Participating children （n 232, 101 males, mean age - 12.3 years） provided a minimum of four monitored days of PA （via accelerometer） and completed a survey assessing moderate-to-vigorous physical activity （MVPA）, sport competence, appearance, enjoyment, and self-efficacy. Height and weight were measured and body mass index （BMI） was calculated. Results： Hierarchical regression models controlling for sex, race, and BMI Z-score showed that only sex and BMI Z-score were significant correlates of objective MVPA while only sex was a significant correlate of objective total PA. However, in a separate model examining the relationship with subjective MVPA, enjoyment of PA and self-efficacy for PA were the only significant correlates of self-reported PA. Conclusion： Measuring MVPA via self-report versus accelerometry produces considerably different results in a sample of young adolescents. Future studies should use caution when selecting outcome measures if the intent is to identify modifiable correlates of MVPA in youth.

Voidage measurement based on genetic algorithm and electrical capacitance tomography

A new voidage measurement method based on electrical capacitance tomography (ECT) technique, Genetic Algo- rithm (GA) and Partial Least Square (PLS) method was proposed. The voidage measurement model, linear capacitance combi- nation, was developed to measure on-line voidage. GA and PLS method were used to determine the coefficients of the voidage measurement model. GA was used to explore the optimal capacitance combination which gave significant contribution to the voidage measurement. PLS method was applied to determine the weight coefficient of the contribution of each capacitance to the voidage measurement. Flow pattern identification result was introduced to improve the voidage measurement accuracy. Experi- mental results showed that the proposed voidage measurement method is effective and that the measurement accuracy is satis- factory.

The advance and development of damage measurement technique of rock

The key problem of rock damage mechanics is that determination of the variable of rock damage and the establishment of damage constitutive relation of rock, which is inevitable involved in the measurement problem of rock. In this paper, the measurement technology and method of rock damage are comprehensively narrated, analyzed and studied. On the basis of the narrating the former study, a new method (Computerized Tomography,CT for short) is introduced, which is applied to rock damage measurement. On the other hand, some newest study results and laws in the field are also introduced, which are from some scholars, the author of this paper.

Technique and experiment of active direct gas pressure measurement in coal roadway

An active measurement method and its principle was introduced consideringthe low success rate,special difficulty,and long measurement time of the direct gas pressuremeasurement currently used in coal roadways.The technology of drilling,boreholesealing depth,borehole sealing length,sealing control of the measuring process,compensatorycomputation of gas loss quantity and other key techniques were discussed.Finally,based on the latest instrument the authors developed,a series of experiments of directgas pressure measurement in the coal roadways of the Jincheng and Tongchuanmine district,were carried out.The experimental results show that active gas pressuremeasurement technique has advantages as follows:(1) the application scope of direct gaspressure measurement technique is wide and it does not have the restriction of coalhardness,coal seam fissure and other conditions;(2) the measured results are credible,which can be tested by the same gas pressure value acquired from a different borehole inthe same place;(3) the measurement process is convenient and quick,it takes about 2 to3 days to acquire the gas pressure value in a coal seam.

Viscosity of food boluses affects the axial force in the esophagus

AIM: To study the effect of viscosity on axial force in the esophagus during primary peristalsis using a newly validated impedance-based axial force recording technique. METHODS: A probe able to simultaneously measure both axial force and manometry was positioned above the lower esophageal sphincter. Potable tap water and three thickened fluids were used to create boluses of different viscosities. Water has a viscosity of 1 mPa·s. The three thickened fluids were made with different concentrations of Clinutren Instant thickener. The viscous fluids were in appearance comparable to pudding (2 kPa·s), yogurt (6 kPa·s) and slush ice (10 kPa·s). Six healthy volunteers swallowed 5 and 10 mL of boluses multiple times. RESULTS: The pressure amplitude did not increase with the bolus viscosity nor with the bolus volume whereas the axial force increased marginally with bolus volume (0.1 > P > 0.05). Both techniques showed that contraction duration increased with bolus viscosity (P < 0.01). Association was found between axial force and pressure but the association became weaker withincreasing viscosity. The pressure amplitude did not increase with the viscosity or bolus volume whereas the axial force increased marginally with the bolus size. CONCLUSION: This indicates a discrepancy between the physiological functions that can be recorded with axial force measurements and pressure measurements.

Research on inspection of stability of subsiding area in composite rock-mass roadway

The research concentrates mainly on the development of failure process in composite rock-mass through acoustic emission, convergence inspection, stress measurement, subside area measurement, level measurement in the process of stability and safety monitoring as well as inspecting of subside area in composite hard rock. In terms of the modern signal analysis technology, various aspects are discussed. The monitoring result and the stability of rock mass can be synthetically evaluated and inferred, and the location of acoustic origin according to the acoustic emission regularity can be successfully detected. Finally the key factors of the deformation can be inferred from in subside area.

Competitive trampolining influence trabecular bone structure,bone size,and bone strength

Background：Trampolining is a form of gymnastics that has increased in popularity over the last decade and due to its concurrence with the formative years of bone development,it may have an important impact on bone health.However,bone density,microarchitecture,and bone strength of competitive trampolinists have not been explored.Therefore,the purpose of this cross-sectional study was to investigate the relationship between trampolining participation and（1） bone density,area,and microarchitecture;and（2） estimated bone strength and the role of muscle and impact loading in young female adults.Methods：We recruited 29 female participants aged 16–29 years for this study（n=14 trampolinists;n=15 controls）.Skeletal parameters were assessed using dual X-ray absorptiometry,high-resolution peripheral quantitative computed tomography（HR-pQCT）,and finit element analysis（FEA）.Muscle strength was measured using dynamometers.Results：Trampolinists had higher bone density at the hip and spine,greater trabecular density and thicker trabeculae at the tibia,as well as larger bones at both the tibia and radius than controls（p〈0.05）.Trampolinists also had higher muscle strength than controls at the lower body with no difference between groups in the upper body.Estimates of bone strength using FEA were greater for trampolinists than controls at both the radius and tibia.Conclusion：This is the firs study to investigate bone density,area,and microarchitecture in female trampolinists using HR-p QCT.Trampolinists had greater bone density,area,microarchitecture,and estimated bone strength than controls.

Measurement and Correlation of Vapor-Liquid Equilibrium of the 1,2-Epoxycyclohexane-Cyclohexanone Binary System at 101.3kPa

Many by-products are generated in the process of oxidizing cyclohexene to produce 1,2-epoxycyclohexane by hydrogen peroxide, including cyclohexanol, cyclohexanone, etc. To obtain high-purity 1,2-epoxycyclohexane, the by-products must be removed through rectification. Refining 1,2-epoxycyclohexane through rectification requires vapor-liquid equilibrium(VLE) data of the related system. Therefore, the VLE data of 1,2-epoxycyclohexane- cyc-lohexanone system were measured at 101.3 kPa using an improved EC-2 VLE still. The thermodynamic consistency of the data was then tested by Herington's method and the rigorous point-to-point method. The results obtained were exemplary. The VLE data were correlated by the Wilson and non-random two-liquid(NRTL) equations, using the error sum squares of the vapor composition as the objective function to obtain the model parameters. The difference between the calculated values and the experimental data is minor, indicating that the VLE data are suitable for engineering design.

Strain measurement using frequency modulation fiber optic interferometer

The method for measuring the strain of an object using an optical fiber and a frequency modulation(FM) coupled cavity semiconductor laser is proposed.This method uses the coherent FM heterodyne principle of the Michelson interferometer and can avoid the π/2 nonreciprocal phase bias and phase shifting problem existing in general fiber optic interferential sensors, the maximum detection range is limited by the coherent length of the semiconductor laser and its relative factor.

Fluent-based numerical simulation of flow centrifugal fan

Testing centrifugal fan flow field by physical laboratory is difficult because the testing system is complex and the workload is heavy, and the results observed by naked-eye deviates far from the actual value. To address this problem, the computational fluid dynamics software FLUENT was applied to establish three-dimensional model of the centrifugal fan. The numeral model was verified by comparing simulation data to experimental data. The pressure centrifugal fan and the speed changes in distribution in centrifugal fan was simulated by computational fluid dynamics soft-ware FLUENT. The simulation results show that the gas flow velocity in the impeller increases with impeller radius increase. Static pressure gradually increases when gas from the fan access is imported through fan impeller leaving fans.

Implementation of Vibrancy Awaking Pressure Measuring Instrument for Single Hydraulic Prop

An instnmaent awakened by means of vibration for single hydraulic prop pressame measuring is described in this paper. The principle and implementation of this metlmd are introduced in detail. The instnznent uses the hgh-perftmnance single chip C8051F310 as its MCU and vibration sensor as its awaking device. It has such advantages as small vohane and low power consmnption, and moreover it could resolve the problem that traditional pressure measming instrument on single hydraulic prop can＇t be used in coal mine.