Predicting Interfacial Loads between the Prosthetic Socket and the Residual Limb for Below-Knee Amputees – A Case Study

Abstract:  In this study, an artificial neural network (ANN) was deployed as a tool to determine the internal loads between the residual limb and prosthetic socket for below-knee amputees. This was achieved by using simulated load data to validate the ANN and captured clinical load data to predict the internal loads at the residual limb–socket interface. Load/pressure was applied to 16 regions of the socket, using loading pads in conjunction with a load applicator, and surface strains were collected using 15 strain gauge rosettes. A super-position program was utilised to generate training and testing patterns from the original load/strain data collected. Using this data, a back-propagation ANN, developed at the University of the West of England, was trained. The input to the trained network was the surface strains and the output the internal loads/pressure. The system was validated and the mean square error (MSE) of the system was found to be 8.8% for 1000 training patterns and 8.9% for 50 testing patterns, which was deemed an acceptable error. Finally, the validated system was used to predict pressure-sensitive/-tolerant regions at the limb–socket interface with great success.     

Synthesis and characterization of silica aerogels by a novel fast ambient pressure drying process

Using cheap waterglass as silica source, silica aerogels were synthesized via a novel fast ambient drying by using an ethanol/trimethylchlorosilane (TMCS)/Heptane solution for modification of the wet gel. One-step solvent exchange and surface modification were simultaneously progressed by immersing the hydrogel in EtOH/TMCS/Heptane solution, in which TMCS reacting with pore water and Si–OH group on the surface of the gel, with ethanol and heptane helping to decrease the rate of TMCS reacting with pore water and extrude water from gel pores. The synthesized silica aerogel was a light and crack-free solid, with the density of 0.128–0.136 g/cm³ and 93.8–94.2% porosity. The microstructure, morphology and properties of the aerogels were studied by FTIR, SEM, TEM and BET measurement. The results indicate that silica aerogels exhibit a sponge structure with uniform nano-particle and pores size distribution. The specific surface areas of silica aerogels are 559–618 m²/g. And there is an obvious Si–CH₃ group on the surface of the silica aerogel.     

Photocatalytic TiO2 films deposited by reactive magnetron sputtering with unipolar pulsing and plasma emission control systems

TiO₂ films with thickness of about 500 nm were deposited on unheated non-alkali glass substrates by reactive magnetron sputtering using one Ti metal target with unipolar pulsed powering of 50 kHz and the plasma emission feedback system (PCU). In order to keep the very high deposition rate, the depositions were carried out in the “transition region” between the metallic and the reactive (oxide) sputter mode where the target surface was metallic and oxidized, respectively. Stable deposition was successfully carried out in the whole “transition region” with PCU at total gas pressure of 3.0 Pa. All the as-deposited films deposited in the “transition region” showed amorphous structure, which performed very low photocatalytic activity. After the post-annealing in air at higher than 300 °C, all the films crystallized to anatase polycrystalline structure. They performed both photoinduced decomposition of acetaldehyde and photoinduced hydrophilicity under UV light illumination. The highest deposition rate in this study to deposit the photocatalytic TiO₂ films in the “transition region” was 90 nm/min, which was over twenty times higher than that for conventional sputter deposition processes.     

飞机模型带动力风洞实验高功率密度电机研制

针对飞机模型带动力风洞实验要求驱动电机功率大、尺寸小和转速高的特点，结合某型号飞机实验用16kW电机的研制，提出了根据电机功率密度要求，通过类比法获得长时工作制电机的发热时间常数，计算获得短时工作制条件下电机的初步额定功率，进行电磁及结构优化设计和发热校核，最后进行电机轴的强度和刚度校核设计，同时介绍了地面空载和负载实验方法。     

渐扩切向槽角度对低压燃油雾化喷嘴流动特性影响的数值研究

油枪点火与助燃在燃煤锅炉上应用较为普遍，但在应用中油喷嘴雾化所需的压力较高（2.0~2.5MPa），耗油量较大，使整个油系统的维护工作量增大，并影响运行的经济性。为减小运行压力，文中提出有渐扩切向槽式旋流雾化油喷嘴，建立了有渐扩切向槽旋流雾化喷嘴的三维流动数学模型，采用k-e /RNG模型和SIMPLE方法数值模拟了有渐扩切向槽偏转角的低压燃油喷嘴的流动特性，并对不同渐扩切向槽角度q时的喷嘴流动特性进行了比较，结果表明：渐扩切向槽的偏转角q大小对其流动特性影响较大，偏转角q不能为负值，因其能量损失较大；当渐扩角度q=6°时，其能量损失最小，喷嘴内轻柴油流动刚好形成实心的锥体，喷嘴回流刚好消失，此后，随着q的增加，能量损失也增加；切向槽只要存在渐扩角度，其能量损失均小于无渐扩(缩)角度的情况，切向槽外扩角度(正值)的能量损失小于切向槽内扩角度。     

一种测量真空开关灭弧室真空度的新方法

提出了一种无需施加磁场、利用发射电流衰减速度测量真空开关灭弧室真空度的新方法。首先利用500μA发射电流对触头表面轰击,除去触头表面上多余的分子吸附层。然后利用35μA发射电流与触头间残余气体分子的碰撞电离,形成离子流。离子流又撞击触头表面,被表面捕获,形成新增吸附层。这些新增吸附层的存在会增大触头材料逸出功,导致发射电流的衰减。真空度不同,发射电流的衰减速度就不同,故在发射电流衰减量一定的条件下,通过检测发射电流衰减时间就可以测量灭弧室内的真空度。文中通过理论分析,给出了发射电流衰减时间与真空度的关系并进行了实验验证。     

管壳式换热器壳侧传热与阻力性能的实验研究与预测

设计并建立了换热器传热与阻力的综合性能实验台,对1种弓形折流板换热器和2种连续螺旋折流板换热器壳侧的传热及阻力性能进行了实验研究,实验介质管侧为水,壳侧为油;同时基于壳侧传热实验数据;应用遗传算法预测了换热器的总换热量。实验结果表明:在相同的壳侧流量下,螺旋折流板换热器的阻力要高于弓型折流板换热器,正进正出螺旋折流板换热器的阻力高于侧进侧出螺旋折流板换热器;螺旋折流板换热器的换热系数高于弓型折流板换热器,侧进侧出螺旋折流板换热器高于正进正出螺旋折流板换热器,而且流量越大这种优势越明显。预测结果表明通过遗传算法得到的传热关联式所得的换热量比采用线性回归所得的更加接近实验数据,表明遗传算法可应用于工程中换热设备性能的预测。     

循环流化床锅炉的模糊自整定汽压控制系统

在分析研究循环流化床锅炉燃烧率扰动下汽压被控对象动态特性的基础上，提出一种新型模糊自适应PID汽压控制系统的设计方法。这种方法直接将影响研究对象特性的工况参数与控制系统的控制器参数联系起来，建立模糊粗调机制，然后根据实际系统误差及其变化率进一步微调控制器参数。仿真结果表明，用这种方法建立的汽压控制系统具有较好的控制品质和较强的适应能力。     

ANSYS软件在高功率密度异步电机定子热分析中的应用

介绍了应用ANSYS自带的APDL编程语言进行软件开发的经验。将该软件应用于高功率密度异步电机定子热分析中。实现了该电机定子自动建模、自动施加载荷的功能，使用和修改都很方便。并且计算速度快。通过对该电机定子温度场计算结果的后处理，得出了该电机定子运行在不同时间段里的温度分布图，以及该电机定子壳体任一节点的温升曲线。     

基于PLC的多泵循环变频恒压供水系统

本文介绍了恒压供水用变频调速技术和PLC控制技术。系统具有节能、工作可靠、自动化程度高、提高供水质量的特点。