基于LabVIEW软件的虚拟数字超声探伤仪设计

传统的仪器一般开发周期较长,分析测试的精度低、成本高。虚拟仪器是利用计算机显示器的显示功能来模拟传统仪器的控制面板,以多种形式输出检测结果;利用软件功能实现数字信号的运算、分析和处理;利用输入/输出(I/O)接口设备完成信号的采集、测量与调试,从而完成各种测试功能的一种计算机仪器系统。采用LabVIEW应用软件对数字式超声探伤仪面板和部分功能进行设计与构建,并实现其相关功能。     

液压系统设计与试验的虚拟样机技术

本文在介绍了虚拟样机技术的基础上，分析和阐述了开发具有虚拟样机功能的液压系统设计与试验软件的模型。     

一种用于数控车削几何仿真的算法

利用开放式三维图形程序标准OpenGL函数库及CAD\CAM软件Pro／E，建立具有真实感的虚拟加工环境，通过对被加工零件离散化，将毛坯表面离散成三角形网格，实现数控车削加工过程的实时仿真。     

Virtual machining considering dimensional,geometrical and tool deflection errors in three-axis CNC milling machines

Virtual manufacturing systems can provide useful means for products to be manufactured without the need of physical testing on the shop floor. As a result, the time and cost of part production can be decreased. There are different error sources in machine tools such as tool deflection, geometrical deviations of moving axis and thermal distortions of machine tool structures. Some of these errors can be decreased by controlling the machining process and environmental parameters. However other errors like tool deflection and geometrical errors which have a big portion of the total error, need more attention. This paper presents a virtual machining system in order to enforce dimensional, geometrical and tool deflection errors in three-axis milling operations. The system receives 21 dimensional and geometrical errors of a machine tool and machining codes of a specific part as input. The output of the system is the modified codes which will produce actual machined part in the virtual environment.     

Detecting similarities in virtual machine behavior for cloud monitoring using smoothed histograms

The growing size and complexity of cloud systems determine scalability issues for resource monitoring and management. While most existing solutions consider each Virtual Machine (VM) as a black box with independent characteristics, we embrace a new perspective where VMs with similar behaviors in terms of resource usage are clustered together. We argue that this new approach has the potential to address scalability issues in cloud monitoring and management. In this paper, we propose a technique to cluster VMs starting from the usage of multiple resources, assuming no knowledge of the services executed on them. This innovative technique models VMs behavior exploiting the probability histogram of their resources usage, and performs smoothing-based noise reduction and selection of the most relevant information to consider for the clustering process. Through extensive evaluation, we show that our proposal achieves high and stable performance in terms of automatic VM clustering, and can reduce the monitoring requirements of cloud systems.     

Present it like it is here: Creating local presence to improve online product experiences

Advanced online product presentation technologies such as virtual mirrors enable consumers to experience products like they are actually present with them in the real world. This study is one of the first to address the mechanism underlying this phenomenon. Inspired by literature on media technology the concept of local presence is put forward and applied to the online consumer behavior domain. A key objective of this paper is to examine whether local presence adds to our understanding of how emerging product presentation formats influence online product experiences. To this end, a laboratory experiment (N = 366) was conducted with product presentation format as a three level (pictures, 360-spin rotation, and virtual mirror) independent variable, allowing for a comparison of the effectiveness of different presentation formats in creating perceptions of local presence. As a second objective, the influence of local presence on perceptions of product tangibility and product likability, two key facets of the online product experience, were assessed. The results, obtained with the use of analysis of variance and partial least squares modeling, show the superiority of the virtual mirror in creating local presence, and demonstrate that local presence is highly predictive of product tangibility and product likability. Theoretical and managerial implications are discussed.     

The psychological functions of avatars and alt(s): A qualitative study

Prior research has shown that approximately 50% of active participants in the 3D virtual world of Second Life have one or more secondary avatars or “alts” in addition to their primary avatar. Thus, these individuals are operating a “multiple or poly-identity system” composed of a physical self, a primary avatar, and one or more alts. However, little is known about the functions these virtual identities serve for the virtual-world user. The current study involved qualitative analysis of semistructured interviews with Second Life participants (N = 24) who had a primary avatar and at least one alt. Interviews were coded to examine the functions that primary avatars and alts served. Eight functions—seven suggested by previous research on virtual world identity and one that emerged from analyses—were reflected in a large majority of the transcribed interviews and are described in the article. The current findings add to our understanding of how multifaceted identity systems operate, as more individuals augment their physical self with a set of virtual identities.     

Evaluation of a haptics-based virtual reality temporal bone simulator for anatomy and surgery training

Introduction

Virtual reality simulation training may improve knowledge of anatomy and surgical skills. We evaluated a 3-dimensional, haptic, virtual reality temporal bone simulator for dissection training.

Methods

The subjects were 7 otolaryngology residents (3 training sessions each) and 7 medical students (1 training session each). The virtual reality temporal bone simulation station included a computer with software that was linked to a force-feedback hand stylus, and the system recorded performance and collisions with vital anatomic structures. Subjects performed virtual reality dissections and completed questionnaires after the training sessions.

Results

Residents and students had favorable responses to most questions of the technology acceptance model (TAM) questionnaire. The average TAM scores were above neutral for residents and medical students in all domains, and the average TAM score for residents was significantly higher for the usefulness domain and lower for the playful domain than students. The average satisfaction questionnaire for residents showed that residents had greater overall satisfaction with cadaver temporal bone dissection training than training with the virtual reality simulator or plastic temporal bone. For medical students, the average comprehension score was significantly increased from before to after training for all anatomic structures. Medical students had significantly more collisions with the dura than residents. The residents had similar mean performance scores after the first and third training sessions for all dissection procedures.

Discussion

The virtual reality temporal bone simulator provided satisfactory training for otolaryngology residents and medical students.     

A low-cost real time virtual system for postural stability assessment at home

Background and objective

The degeneration of the balance control system in the elderly and in many pathologies requires measuring the equilibrium conditions very often. In clinical practice, equilibrium control is commonly evaluated by using a force platform (stabilometric platform) in a clinical environment.In this paper, we demonstrate how a simple movement analysis system, based on a 3D video camera and a 3D real time model reconstruction of the human body, can be used to collect information usually recorded by a physical stabilometric platform.

Methods

The algorithm used to reconstruct the human body model as a set of spheres is described and discussed. Moreover, experimental measurements and comparisons with data collected by a physical stabilometric platform are also reported. The measurements were collected on a set of 6 healthy subjects to whom a change in equilibrium condition was stimulated by performing an equilibrium task.

Results

The experimental results showed that more than 95% of data collected by the proposed method were not significantly different from those collected by the classic platform, thus confirming the usefulness of the proposed system.

Conclusions

The proposed virtual balance assessment system can be implemented at low cost (about 500$) and, for this reason, can be considered a home use medical device. On the contrary, astabilometric platform has a cost of about 10,000$ and requires periodical calibration. The proposed system does not require periodical calibration, as is necessary for stabilometric force platforms, and it is easy to use. In future, the proposed system with little integration can be used, besides being an emulator of a stabilometric platform, also to recognize and track, in real time, head, legs, arms and trunk, that is to collect information actually obtained by sophisticated optoelectronic systems.     

A virtual actuator and sensor approach for fault tolerant control of LPV systems

In this paper, a fault tolerant control (FTC) strategy using virtual actuators and sensors for linear parameter varying (LPV) systems is proposed. The main idea of this FTC method, initially developed for LTI systems, is to reconfigure the control loop such that the nominal controller could still be used without need of retuning it. The plant with the faulty actuator/sensor is modified adding the virtual actuator/sensor block that masks the actuator/sensor fault. The suggested technique is an active FTC strategy that reconfigures the virtual actuator/sensor on-line taking into account faults and operating point changes. The stability of the reconfigured control loop is guaranteed if the faulty plant is stabilizable/detectable. The LPV virtual actuator/sensor is designed using polytopic LPV techniques and linear matrix inequalities (LMIs). A two-tank system simulator is used to assess the performance of the proposed method. In particular, it is shown that the application of the proposed technique results in an improvement, in terms of performance, with respect to the LTI counterpart.