小型环境风洞三维移测机

介绍一种适用于小型环境风洞的三维移测机的基本结构和运动原理以及为减小风阻及扰流采取的措施,给出了以PLC+HMI为核心的控制系统硬件结构及控制策略。实际运行结果表明:此系统对风洞流场干扰小,定位准确,运行稳定。

Quantitative evaluation of long-term liver repopulation and the reconstitution of bile ductules after hepatocellular transplantation

AIM： The treatment of liver disease is severely limited by a shortage of donor livers. In trying to address this growing problem, hepatocellular transplantation （HTx） has received much attention as an alternative to whole organ transplant. However, the expansion of transplanted cells is at low level, and the reconstitution of functional liver tissue is limited by this cellular property. We set up an animal model to better understand cell dose effect and the kinetics of liver repopulation following HTx. METHODS： Dipeptidyl peptidase Ⅳ （DPPⅣ）-deficient rats treated with retrorsine and subjected to partial hepatectomy were infused with DPPⅣ-positive hepatocytes. Rats were injected with varying numbers of donor hepatocytes down to 100 cells low, and liver repopulation was examined at different time points up to 20 mo long. Repopulation was assessed by computer-aided quantitative detection. RESULTS： Transplanted hepatocytes underwent multiple rounds of proliferation and stably repopulated the injured livers after 20 mo and at all cell doses. Transplanted cells divided 14 times within the 3-mo time period following infusion, and the liver repopulation reached a plateau between 3 and 20 too. Approximately 90% replacement occurred. Donor-derived cells also reconstituted the bile ductules of the recipients. CONCLUSION： The ability of transplanted hepatocytes to fully reconstitute injured livers strongly supports further investigation into the clinical potential of HTx. Additionally, the observation that transplanted hepatocytes also form components of the biliary system suggests that these cells may have bi-potential property of the stem cells.

Fault detection and identification for dead reckoning system of mobile robot based on fuzzy logic particle filter

To deal with fault detection and diagnosis with incomplete model for dead reckoning system of mobile robot,an integrative framework of particle filter detection and fuzzy logic diagnosis was devised.Firstly,an adaptive fault space is designed for recognizing both known faults and unknown faults,in corresponding modes of modeled and model-free.Secondly,the particle filter is utilized to diagnose the modeled faults and detect model-free fault according to the low particle weight and reliability.Especially,the proposed fuzzy logic diagnosis can further analyze model-free modes and identify some soft faults in unknown fault space.The MORCS-1 experimental results show that the fuzzy diagnosis particle filter(FDPF) combinational framework improves fault detection and identification completeness.Specifically speaking,FDPF is feasible to diagnose the modeled faults in known space.Furthermore,the types of model-free soft faults can also be further identified and diagnosed in unknown fault space.

Obstacle detection of mobile robot based on data fusion

To study the problem of obstacle detection based on multi-sensors data fusion,the multi-target tracking theory and techniques are introduced into obstacle detection systems,and the exact position of obstacle can be determined.Data fusion problems are discussed directly based on achievable data from some sensors without considering the specific structure of each individual sensor.With respect to normal linear systems and nonlinear systems,the corresponding algorithms are proposed.The validity of the method is confirmed by simulation results.

Prediction of ground surface displacement caused by grouting

Ground surface displacement caused by grouting was calculated with stochastic medium theory. Ground surface displacement was assumed to be caused by the cavity expansion of grouting, slurry seepage, and slurry contraction. A prediction method of ground surface displacement was developed. The reliability of the presented method was validated through a comparison between theoretical results and results from engineering practice. Results show that the present method is effective. The effect of parameters on uplift displacement was illustrated under different grouting conditions. Through analysis, it can be known that the ground surface uplift is mainly caused by osmosis of slurry and the primary influence angle of stratum β determines the influence range of surface uplift. Besides, the results show that ground surface uplift displacement decreases notably with increasing depth of the grouting cavity but it increases with increasing diffusion radius of grout and increasing grouting pressure.

Motion design of a hybrid wheeled/legged robot for lunar exploration

The robot consists of a quadruped mechanism and two active dual-wheel casters possesses the advantages of wheeled and legged mechanism, and can quickly move on the relatively plane ground with the wheeled mechanism, and can walk on the extremely uneven terrain with the legged mechanism. The effectiveness of the motion design of the hybrid robot is iHustrated by simulation results.

Navigation of Robot Using VFH＋ Algorithm

This paper describes a reactive navigation proposed for a differentially driven robot. The aim of the reactive navigation is to prescribe behavior to the robot based on actual sensor values that is collision-free. Analysis of reactive navigation methods shows that there is no reliable reactive collision-free method. However, method VFH＋ is suboptimal reactive navigation method for static environment. Original method was proposed for ultrasonic rangefinders. Nowadays, much more sophisticated sensors are available. That is why our modification is proposed for a laser rangefinder attached to indoor mobile robot. Results are presented as simulation in Matlab and also as experiments with real robot. Based on these experiments, it can be claimed that VFH＋ is very effective reactive navigation method for various sensors and environments and it can be modified for different requirements on robot behavior.

Research on the mining roadway displacement forecasting based on support vector machine theory

In view of the difficulty in supporting the surrounding rocks of roadway 3-411 ofFucun Coal Mine of Zaozhuang Mining Group, a deformation forecasting model was putforward based on particle swarm optimization.The kernel function and model parameterswere optimized using particle swarm optimization.It is shown that the forecast result isvery close to the real monitoring data.Furthermore, the PSO-SVM (Particle Swarm Optimization-Support Vector Machine) model is compared with the GM(1,1) model and L-M BPnetwork model.The results show that PSO-SVM method is better in the aspect of predictionaccuracy and the PSO-SVM roadway deformation pre-diction model is feasible for thelarge deformation prediction of coal mine roadway.

A Quantitative Security Metric Model for Security Controls:Secure Virtual Machine Migration Protocol as Target of Assessment

Quantitative security metrics are desirable for measuring the performance of information security controls. Security metrics help to make functional and business decisions for improving the performance and cost of the security controls. However, defining enterprise-level security metrics has already been listed as one of the hard problems in the Info Sec Research Council's hard problems list. Almost all the efforts in defining absolute security metrics for the enterprise security have not been proved fruitful. At the same time, with the maturity of the security industry, there has been a continuous emphasis from the regulatory bodies on establishing measurable security metrics. This paper addresses this need and proposes a relative security metric model that derives three quantitative security metrics named Attack Resiliency Measure(ARM), Performance Improvement Factor(PIF), and Cost/Benefit Measure(CBM) for measuring the performance of the security controls. For the effectiveness evaluation of the proposed security metrics, we took the secure virtual machine(VM) migration protocol as the target of assessment. The virtual-ization technologies are rapidly changing the landscape of the computing world. Devising security metrics for virtualized environment is even more challenging. As secure virtual machine migration is an evolving area and no standard protocol is available specifically for secure VM migration. This paper took the secure virtual machine migration protocol as the target of assessment and applied the proposed relative security metric model for measuring the Attack Resiliency Measure, Performance Improvement Factor, and Cost/Benefit Measure of the secure VM migration protocol.

SIMULATION OF STRATA MOVEMENTS DUE TO UNDERGROUND MINING USING AN AUTOMATED MEASUREMENT SYSTEM FOR EQUIVALENT MATERIAL MODELING FACILITY

Strata movement simulation was conducted in an equivalent material modeling facility developed by the Department of Mining Engineering, Southern Illinois University at Carbondale, under U. S. Bureau of Mines contracts. An innovative displacement measurement system called videogrammetric system was developed and utilized for recording, measuring and analyzing the deformation and failure process of the models. A room and pillar mining and a longwall mining prototypes were studied in the modeling. Study found that weak floor of coal seam plays an important role in pillar stability and therefore the overburden movements.

A new optimal approach to segmentation of 2D range scans to line sections

In order to obtain a compact and exact representation of 2D range scans,UKF(unscented Kalman filter) and CDKF(central difference Kalman filter) were proposed for extracting the breakpoint of the laser data. Line extraction was performed in every continuous breakpoint region by detecting the optimal angle and the optimal distance in polar coordinates,and every breakpoint area was constructed with two points. As a proof to the method,an experiment was performed by a mobile robot equipped with one SICK laser rangefinder,and the results of UKF/CDKF in breakpoint detection and line extraction were compared with those of the EKF(extended Kalman filter) . The results show that the exact geometry of the raw laser data of the environments can be obtained by segmented raw measurements(combining the proposed breakpoint detection approach with the line extraction method) ,and method UKF is the best one compared with CDKF and EKF.

Development of a Methodology for Determination and Analysis of Thermal Displacements of Machine Tools Using Finite Elements Method and Artificial Neural Network

In the processes of manufacturing, MT （machine tools） plays an important role in the manufacture of work pieces with complex and high dimensional and geometric accuracy. Much of the errors of a machine tool are those which are thermally induced which are from internal and external heat sources acting on the machine. In this paper, a methodology for determining and analyzing the thermal deformation of machine tools using FEM （finite element method） and ANN （artificial neural networks） is presented. After modeling the machine using FEM is defined the location of the heat sources, it is possible to obtain the temperature gradient and the corresponding thermal deformation at predetermined periods. Results obtained with simulations using the software NX.7.5 showed that this methodology is an effective tool in determining the thermal deformation of the machine, correlating the temperature reading at strategic points with volumetric deformation at the tool tip. Therefore, the thermal analysis of the errors in the pair tool part can be established. After training and validation process, the network will be able to make the prediction of thermal errors just stating the temperature values of specific points of each heat source, providing a way for compensation of thermally induced errors.

Research on Improving Directional Stability for Airborne Laser Designator

The major purpose of this paper is to reduce the laser directional deviation of laser designator on a moving platform.A new method of inhibiting the laser beam positional error caused by platform movement and vibration is proposed.In this method,quadrant detector(QD)and fast steering mirror are combined to measure the angle between laser designator axis and the line-of-sight of the target,then a control signal composed with the angle errors is generated to aim the axis of the laser designator at the target steadily.This is a real time processing method and it is suitable for airborne laser-guided weapons with second-class guiding time.

YD/T 1885-2009 Technical Requirements and Test Methods for Wired Headset Interface of Mobile Communication Terminal

The communications industrial standard YD/T 1885-2009 provides the types of headset interfaces, the performance requirements and test methods. Since the release of this standard, more and more manufacturers have adopted the concentric connector, which gives more choices to consumers and also has benefits on the environmental protection and the healthy development of the mobile terminal industry. Now, the universal headset interface has been included in the draft ITU-T recommendation P.381. lts internationalization will further enhance the universality of the mobile phone headset interlace. It is China＇s another great contribution to the international standardization following the standard of universal power adapter for mobile phones.

A displacement-relay videometric method for surface subsidence surveillance in unstable areas

When measuring the surface subsidence of unstable areas such as railroad beds and large construction fields, it is not practical to always find stable positions to install measurement instruments. Yet installing those instruments in unstable positions will cause measurement errors or even the complete failure of long-term subsidence surveillance. In this paper, the innovative concept and its method of "displacement-relay videometrics" are proposed. With the method, a double-headed camera is designed, and two constraints, the "fixation constraint" and the "homologous constraint", are established to construct the displacement-relay measurement equations, which can concurrently give the subsidence of the points to be measured and the positions where the cameras are fixed. The method and its measurement system are thus capable of automatically measuring the surface subsidence under the condition that the cameras are mounted on unstable locations over long durations. Therefore, the method has the broad prospect of undertaking automatic, long-term and continuous measurement for surface subsidence in engineering projects such as railroad beds, bridges and the ground beds of tall buildings. The proposed method opens a new area that cameras can be mounted on unstable platform to make high accuracy measurements, which is of great significance for applications.

Biomechanical researches on tissue engineering bone constructed by deproteinated bone

Objective： To study biomechanical changes of newly formed bones 24 weeks after repairing large defects of long bones of goats using heterogeneous deproteinated bone （DPB） prepared by modified methods as an engineering scaffold. Methods： According to a fully randomized design, 18 goats were evenly divided into three groups： normal bone control group （Group A）, autologous bone group （Group B） and experimental group （Group C）. Each goat in Groups B and C were subjected to the periosteum and bone defect at middle-lower part of the right tibia （20% of the whole tibia in length）, followed by autologous bone or DPB plus autolognus MSCs ＋ rhBMP2 implantation, respectively and semi- ring slot fixation; while goats in Group A did not perform osteotomy. At 24 weeks after surgery, biomechanical tests were carried out on the tibias. Results： At 24 weeks after surgery, the results of anticompression test on tibias in three groups were recorded by a functional recorder presented as linear pressure-deformation curve. The shapes of the curves and their change tendency were similar among three groups. The ultimate pressure values were 10.74 MPa±1.23 MPa, 10. 11 MPa±1.35 MPa and 10.22 MPa±1.32 MPa and fracture compression rates were 26.82%±0.87%, 27.17%±0.75% and 28.22%±1.12% in Groups A, B and C, respectively. Comparisons of anti-compression ultimate pressures and fracture compression rates among three groups demonstrated no significant difference （PAB=0.415, PBC=0.494）. Three-point antibend test on tibias was recorded as load-deformation curves, and the shapes of the curves and their change tendency were similar among three groups. The ultimate pressure values of the anti-bend test were 481.52 N±12.45 N, 478.34 N±14.68 N and 475.62 N±13.41 N and the fracture bend rates were 2.62 mm±0.12 mm, 2.61 mm±0.15 mm and 2.81 mm±0.13 mm in Groups A, B and C, respectively. There was no significant difference between groups （PAB=0.7, PBc=0.448）. The ultimate anti-torsion torque values were 6.55 N.mi-0.25 N.m, 6.34 N＇m^0.18 N＇m and 6.42 N＇m^0.21 N＇m and fracture torsion rates were 29.51°±1.64°, 28.88±1.46° and 28.81°±1.33° in Groups A, B and C, respectively. There was no significant difference between groups （PAB=0.123, PBc=0.346）. Conclusions： The biomechanical characteristics of newly formed bones from heterogeneous DPB for repairing large segmental long bone defect are comparable to those of normal bones and autologous bones. DPB has the potential for clinical usage as bone graft material.

Volatile organic compounds sensing based on Bennet doubler-inspired triboelectric nanogenerator and machine learning-assisted ion mobility analysis

Ion mobility analysis is a well-known analytical technique for identifying gas-phase compounds in fastresponse gas-monitoring systems.However,the conventional plasma discharge system is bulky,operates at a high temperature,and inappropriate for volatile organic compounds(VOCs)concentration detection.Therefore,we report a machine learning(ML)-enhanced ion mobility analyzer with a triboelectric-based ionizer,which offers good ion mobility selectivity and VOC recognition ability with a small-sized device and non-strict operating environment.Based on the charge accumulation mechanism,a multi-switched manipulation triboelectric nanogenerator(SM-TENG)can provide a direct current(DC)bias at the order of a few hundred,which can be further leveraged as the power source to obtain a unique and repeatable discharge characteristic of different VOCs,and their mixtures,with a special tip-plate electrode configuration.Aiming to tackle the grand challenge in the detection of multiple VOCs,the ML-enhanced ion mobility analysis method was successfully demonstrated by extracting specific features automatically from ion mobility spectrometry data with ML algorithms,which significantly enhance the detection ability of the SM-TENG based VOC analyzer,showing a portable real-time VOC monitoring solution with rapid response and low power consumption for future internet of things based environmental monitoring applications.