DPC：基于增强现实儿童绘本的多视角评估框架

 增强现实(AR)技术作为沟通现实与虚拟场景的桥梁,能够激发使用者的想象力、 空间感和创造力。现有 AR 儿童绘本在虚实结合方面不足、游戏形式和互动种类单一,缺少寓 教于乐的AR儿童绘本游戏作为内容。首先试用和研究了59款移动AR游戏并分类。使用Delphi 法选择了一些合适的游戏类型,并将其迁移到儿童绘本上。再让 6~12 岁儿童(n=6)试玩并进行 观察和访谈。同时,组织家长/老师(n=7)与开发者(n=5)形成焦点小组并针对绘本和应用进行讨 论。最终,提取了开发者(developer)、家长/老师(parents/teachers)和孩子(children)对于 AR 儿童 绘本不同的需求和对应指标,收获了对应 3 个维度的框架 DPC (developer, parents/teachers, children),且每个维度被细分。使用 DPC 框架对 AR 儿童绘本游戏进行了改进。     

Young children’s computer skills development from kindergarten to third grade

This investigation explores young children’s computer skills development from kindergarten to third grade using the Early Childhood Longitudinal Study–Kindergarten (ECLS–K) dataset. The sample size of the study was 8642 children. Latent growth curve modeling analysis was used as an analytical tool to examine the development of children’s computer skills using LISREL software version 8.80. Results indicated, not surprisingly, that the availability of a computer at home and a high socio-economic status were statistically significant predictors of children’s baseline computer skills in kindergarten. The availability of computers in kindergarten, however, was a statistically significant predictor of the development of children’s computer skills from kindergarten to third grade. Although there was no difference between girls and boys in their baseline computer skills in kindergarten, the rate of development in computer skills was higher for girls than boys. Results suggest that the availability of an adequate level of computers in kindergarten classrooms can help close the initial gap in children’s computer skills due to socio-economic status and lack of computer access prior to entering school. Supplying kindergarten classrooms with adequate computers could positively contribute to children’s long-term development of computer skills.     

基于AR-VR混合技术的儿童智力开发系统研究

传统的儿童智力开发大多采用观看图书或是视频的方式,存在信息表达单一、缺乏生动性、交互性差等缺陷。在儿童智力开发理论基础上,将增强现实技术（AR）与虚拟现实技术（VR）结合,基于Unity3D平台设计,开发出具有游戏式风格的儿童智力开发系统。VR技术用于开发虚拟漫游模块,通过沉浸式交互体验,培养儿童对身边事物的认知及观察能力。AR技术用于开发识图模块,通过3D的学习方式,为儿童传递更丰富更具体的学习体验。实验结果表明,AR-VR混合技术能构建出高度真实的学习环境,具有多感官交互效果,增强儿童对现实环境的感知和学习能力,相较于传统的儿童智力开发,该系统能帮助儿童获得更好的学习体验和交互方式,激发儿童的学习兴趣。     

面向儿童自学的体感交互应用设计

根据儿童独特的思维方式和行为特征,设计一款面向儿童自学的应用系统。该应用系统采用体感交互技术,通过有限姿势序列状态机和碰撞检测方法实现动作识别与碰撞检测。借助游戏娱乐的表现形式使儿童以非接触式交互方式完成学习过程,减轻了儿童的认知负担,同时满足了儿童好动的天性,降低电脑对儿童的伤害。系统类似于切水果的游戏,帮助儿童完成英语单词的记忆,增加儿童学习的乐趣,带动儿童自学的积极性与主动性,以达到娱教结合的目的。      

Effect of process parameters on the surface morphology andmechanical performance of silicon structures after deep reactive ionetching (DRIE)

The ability to predict and control the influence of process parameters during silicon etching is vital for the success of most MEMS devices. In the case of deep reactive ion etching (DRIE) of silicon substrates, experimental results indicate that etch performance as well as surface morphology and post-etch mechanical behavior have a strong dependence on processing parameters. In order to understand the influence of these parameters, a set of experiments was designed and performed to fully characterize the sensitivity of surface morphology and mechanical behavior of silicon samples produced with different DRIE operating conditions. The designed experiment involved a matrix of 55 silicon wafers with radius hub flexure (RHF) specimens which were etched 10 min under varying DRIE processing conditions. Data collected by interferometry, atomic force microscopy (AFM), profilometry, and scanning electron microscopy (SEM), was used to determine the response of etching performance to operating conditions. The data collected for fracture strength was analyzed and modeled by finite element computation. The data was then fitted to response surfaces to model the dependence of response variables on dry processing conditions     

Development of a method for evaluating accessibility of medical equipment for patients with disabilities

ObjectiveThe purpose of this study was to develop a method for evaluating accessibility of medical equipment for patients with disabilities.MethodsThe researchers reviewed videotapes of patient-participants with various physical and sensory disabilities using different types of medical equipment. For each of 11 videotapes, four observers independently identified and documented access and safety barriers, such as physical, sensory, cognitive, and environmental barriers. Inter-observer variability for identifying barrier presence was assessed with kappa statistics for pairs of observers.ResultsA list of 10 access and safety barriers was developed through an iterative consensus process, which identified design features of medical equipment that presented difficulties for participants with disabilities. The list is useful for identifying and categorizing accessibility problems found in equipment. While reliability of barrier identification was substantial or moderate for some barriers, reconciliation of barrier events identified by multiple video observers is recommended for optimal results.     

Development of a method for evaluating accessibility of medical equipment for patients with disabilities

Objective

The purpose of this study was to develop a method for evaluating accessibility of medical equipment for patients with disabilities.

Methods

The researchers reviewed videotapes of patient-participants with various physical and sensory disabilities using different types of medical equipment. For each of 11 videotapes, four observers independently identified and documented access and safety barriers, such as physical, sensory, cognitive, and environmental barriers. Inter-observer variability for identifying barrier presence was assessed with kappa statistics for pairs of observers.

Results

A list of 10 access and safety barriers was developed through an iterative consensus process, which identified design features of medical equipment that presented difficulties for participants with disabilities. The list is useful for identifying and categorizing accessibility problems found in equipment. While reliability of barrier identification was substantial or moderate for some barriers, reconciliation of barrier events identified by multiple video observers is recommended for optimal results.     

Barriers common to mobile and disabled web users

World Wide Web accessibility and best practice audits and evaluations are becoming increasingly complicated, time consuming, and costly because of the increasing number of conformance criteria which need to be tested. In the case of web access by disabled users and mobile users, a number of commonalities have been identified in usage, which have been termed situationally-induced impairments; in effect the barriers experienced by mobile web users have been likened to those of visually disabled and motor impaired users. In this case, we became interested in understanding if it was possible to evaluate the problems of mobile web users in terms of the aggregation of barriers-to-access experienced by disabled users; and in this way attempt to reduce the need for the evaluation of the additional conformance criteria associated with mobile web best practice guidelines. We used the Barrier Walkthrough (BW) method as our analytical framework. Capable of being used to evaluate accessibility in both the disabled and mobile contexts, the BW method would also enable testing and aggregation of barriers across our target user groups.We tested 61 barriers across four user groups each over four pages with 19 experts and 57 non-experts focusing on the validity and reliability of our results. We found that 58% of the barrier types that were correctly found were identified as common between mobile and disabled users. Further, if our aggregated barriers alone were used to test for mobile conformance only four barrier types would be missed. Our results also showed that mobile users and low vision users have the most common barrier types, while low vision and motor impaired users experiencing similar rates of severity in the barriers they experienced. We conclude that the aggregated evaluation results for blind, low vision and motor impaired users can be used to approximate the evaluation results for mobile web users.     

高效无线传感器网络强k-栅栏覆盖节能算法

为了进一步降低监测穿越行为的无线传感器网络强k-栅栏覆盖的能耗,首先证明了强k-栅栏覆盖最小能耗问题是NP难的,进而提出了一个节点感知功率可调的启发式节能算法HARPN。该算法根据栅栏中相邻节点的间距和前向节点的状态制定了4种节点感知半径的计算规则,再根据节点感知半径的大小确定节点的感知功率等级,在保证传感栅栏贯通的前提下,尽可能降低栅栏整体的能耗。理论分析和仿真实验表明,在相同的栅栏波动条件下,HARPN算法的适应性和稳定性更强,网络平均能耗约为Heuristic-2算法的62%,网络的生存期进一步延长。     

无信号控制路段行人过街管理策略研究

现行行人过街管理策略缺乏定量依据。提出无信号控制路段行人安全过街延误模型,在一定路宽、行人流量条件下,以行人延误小于其极限忍耐时间为判定标准,得出一、二次过街适合的机动车流量范围。最后,结合有信号路段的研究得出不同情况下路段行人过街最佳管理策略。     

Risk of tripping,minimum foot clearance,and step length when crossing a barrier

This study was designed to investigate gait parameters upon crossing a barrier and environmental factors influencing the perceived risk of tripping. These factors included illumination and barrier conditions. Barrier conditions were divided into height, type, and color of the barrier. Illumination conditions included normal and dimmed conditions. Twelve male participants were recruited. They walked on a walkway, moving over a barrier. They gave a subjective rating of risk of tripping (SRRT) both before and after the walk. A research assistant recorded a gait disturbance rating (GDR) of the participant upon barrier crossing. The minimum foot clearance (MFC) of both the leading and lagging foot when moving over the barrier, and the step length of the participant before and after crossing the barrier were calculated. The results indicated that the SRRT, both before and after the walk, was significantly (p < 0.0001) higher when the barrier height increased. Increased barrier height caused significantly (p < 0.0001) higher GDR. The barrier type (p < 0.01) and illumination conditions (p < 0.001) had significant effects on the MFC of both the leading and the lagging foot. The color (p < 0.05) and height (p < 0.05) of the barrier also influenced the MFC of the lagging foot significantly. Step length of the leading foot when crossing the barrier was significantly affected by illumination condition (p < 0.001) and barrier type (p < 0.05). The results of the study are helpful in understanding the mechanisms brought into play when moving over barriers on walkways. They provide meaningful information that will help in reducing trip and fall accidents.     

运用栅栏函数验证连续系统的有界时间安全性

栅栏函数在连续系统验证方面有着广泛的应用.其主要想法在于: 在可达集和非安全集之间寻找一个栅栏,从初始区域出发的路径不会越过这个栅栏,而非安全区域在栅栏的另外一端.这样就可以通过寻找栅栏函数来验证一个系统的安全性.近年来,已有一些工作讨论连续系统在无界时间情况下的栅栏函数生成.但是对于有些系统,人们可能只关心其在有界时间内的安全性.因为在无界时间内不安全并不能说明在给定时间内也是不安全的,所以对于这类问题无界时间栅栏函数方法并不适用.受无界时间栅栏函数方法的启发,本文针对有界时间的情况,给出有界时间栅栏函数生成方法.首先给出有界时间栅栏函数的一些充分条件.对于多项式系统,将多项式非负的条件做平方和松弛后利用平方和规划工具求解这些充分条件得到栅栏函数;对于初等系统(包含一些初等函数),先将该初等系统转化为一个多项式系统,然后求解对应多项式系统的栅栏函数.对一些无界时间不安全的实例,演示了我们的方法在验证有界时间安性问题上的有效性.     

Burglars blocked by barriers? The impact of physical and social barriers on residential burglars' target location choices in China

Based on an offender spatial decision-making perspective, this burglary target location choice study aims to understand how physical and social barriers affect why residential burglars commit their crimes at particular locations in a major Chinese city. Using data on 3860 residential burglaries committed by 3772 burglars between January 2012 and June 2016 in ZG city, China, conditional logit (discrete choice) models were estimated to assess residential burglars' target location choice preferences. Three types of physical barriers were distinguished: major roads with access control, major roads without access control, and major rivers. Social barriers were constructed based on the Hukou system to reflect how local and nonlocal residents live segregated lives. Results show that residential burglars are less likely to target areas for which they have to cross a physical barrier and even less likely to do so if they have to cross multiple rivers. Local burglars are more likely to target communities with a majority of local residents than communities with a majority nonlocal population or a mixed community. Such a social barrier was less pronounced for nonlocal burglars. These findings add new insight that physical and social barriers affect, to various degrees, where residential burglars in China commit their crimes.     

Two‐parallax‐barriers‐based autostereoscopic liquid‐crystal display without cross‐talk

Abstract— An autostereoscopic liquid‐crystal display (LCD) consists of two parallax barriers and an LCD including a liquid‐crystal panel, and a backlight panel is proposed. Parallax barrier 1 is located between the backlight panel and the liquid‐crystal panel, and Parallax barrier 2 is located between the liquid‐crystal panel and viewers. The operation principle of the autostereoscopic display and the calculation equations for the parallax barriers are described in detail. The autostereoscopic LCD was developed and produces high‐quality stereoscopic images without cross‐talk at the optimal viewing distance and less cross‐talk than a conventional one based on one parallax barrier at other viewing distances.     

Modelling handgrip strength in the presence of confounding variables: results from the Allied Dunbar National Fitness Survey

Differences in handgrip strength, caused by risk factors such as physical inactivity, will be influenced by ‘confounding’ variables, e.g. age, body size. The aims of the study were to identify the confounding variables associated with handgrip strength and to assess the benefit that physical activity plays in maintaining grip strength within a population, having adjusted for differences in these confounding variables. The most appropriate linear body size dimension associated with grip strength was height rather than demispan. Non-linear associations with age and body mass were also identified. Handgrip strength peaked in the age group 25 – 34 years for male subjects and in the age group 35 44 years for female subjects. Similarly, handgrip strength increased with body mass until it peaked at a body mass of approximately 100 kg for male and 90 kg for female subjects; thereafter a rapid decline in grip strength was observed. Differences in handgrip strength were found to be significantly associated with levels of physical activity even having controlled for differences in age and body size (height, mass and percentage body fat), but the observed association was not linear. The level of physical activity necessary to maintain an optimal level of handgrip strength was found to be a balance of moderate or vigorous occasions of physical activity.     

Impact of backpack type on respiratory muscle strength and lung function in children

We examine the influence of backpack type on lung function and respiratory muscle strength in children. Thirty-seven children were assessed for lung function and inspiratory and expiratory muscle strength under four randomly determined conditions: unloaded erect standing and three conditions carrying 15% of the child's body weight. In these three conditions, children carried the weight on a backpack with bilateral shoulder straps carried over both shoulders, on a backpack with bilateral shoulder straps carried over one shoulder and on a backpack with a mono shoulder strap. Significantly lower forced vital capacity, forced expiratory volume in one second and maximal expiratory pressure were observed when children carried a backpack with a mono shoulder strap compared to the unloaded standing position. In conclusion, the restrictive effect and the decrease in expiratory muscle strength were more pronounced for the backpack with a mono shoulder strap, suggesting that a double strap backpack is preferable to a mono shoulder strap backpack.

Practitioner summary: There is little known about the effect of schoolbags on respiratory muscle function. We investigated the influence of backpack type on lung function and respiratory muscle strength. A backpack with a mono shoulder strap created a restrictive effect and a decrease in strength, suggesting that a double strap backpack is preferable to a mono shoulder strap backpack.     

Modelling handgrip strength in the presence of confounding variables: results from the Allied Dunbar National Fitness Survey

Differences in handgrip strength, caused by risk factors such as physical inactivity, will be influenced by 'confounding' variables, e.g. age, body size. The aims of the study were to identify the confounding variables associated with handgrip strength and to assess the benefit that physical activity plays in maintaining grip strength within a population, having adjusted for differences in these confounding variables. The most appropriate linear body size dimension associated with grip strength was height rather than demispan. Non-linear associations with age and body mass were also identified. Handgrip strength peaked in the age group 25 - 34 years for male subjects and in the age group 35 - 44 years for female subjects. Similarly, handgrip strength increased with body mass until it peaked at a body mass of approximately 100 kg for male and 90 kg for female subjects; thereafter a rapid decline in grip strength was observed. Differences in handgrip strength were found to be significantly associated with levels of physical activity even having controlled for differences in age and body size (height, mass and percentage body fat), but the observed association was not linear. The level of physical activity necessary to maintain an optimal level of handgrip strength was found to be a balance of moderate or vigorous occasions of physical activity.     

基于随机障碍验证的随机连续系统安全性验证

针对一类同时具有随机初始状态和随机微分方程的随机连续系统的安全性验证问题,提出一种基于随机障碍验证以及初始集选择的计算方法。首先,介绍了随机连续系统及其安全性验证的相关知识及概念;然后,讨论了如何对于服从几种不同分布的初始变量确定初始状态集,并根据选定的初始状态集使用随机障碍验证的方法将安全性验证问题转化为多项式优化问题;最后,运用平方和松弛方法将问题转化为平方和规划问题,并利用SOSTOOLS工具求得安全性概率的下界。理论分析以及实验结果表明,所提方法具有多项式时间的复杂度,能有效地给出随机连续系统在无界时间内的安全性概率的下界。     

Systematic multiscale models to predict the compressive strength of self-compacting concretes modified with nanosilica at different curing ages

The evolution of nanotechnology brings materials with novel performance and during last year’s much attempt has been established to include nanoparticles especially nano-silica (NS) into the concrete to improve performance and develop concrete with enhanced characteristics. Generally, NS is incorporated into the self-compacting concrete (SCC) aiming to positively influence the fresh, mechanical, microstructure, and durability properties of the composite. The most important mechanical property for all types of concrete composites is compressive strength. Therefore, developing reliable models for predicting the compressive strength of SCC is crucial regarding saving time, energy, and cost-effectiveness. Moreover, it gives valuable information for scheduling the construction work and provides information about the correct time for removing the formwork. In this study, three different models including the linear relationship model (LR), nonlinear model (NLR), and multi-logistic model (MLR) were proposed to predict the compressive strength of SCC mixtures made with or without NS. In this regard, a comprehensive data set that consists of 450 samples were collected and analyzed to develop the models. In the modeling process, the most important variables affecting the compressive strength such as NS content, cement content, water to binder ratio, curing time from 1 to 180 days, superplasticizer content, fine aggregate content, and coarse aggregate content were considered as input variables. Various statistical assessments such as Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), Scatter Index (SI), OBJ value, and the coefficient of determination (R²) were used to evaluate the performance of the proposed models. The results indicated that the MLR model performed better for forecasting the compression strength of SCC mixtures modified with NS compared to other models. The SI and OBJ values of the MLR model were 18.8% and 16.7% lower than the NLR model, indicating the superior performance of the MLR model. Moreover, the sensitivity analysis demonstrated that the curing time is the most affecting variable for forecasting the compressive strength of SCC modified with NS.

     

Ergonomic design of ticket barriers for use by the travelling public

This paper describes a two-stage study of the performance and acceptability of automatic ticket barriers. The aim of the research was to provide information to both manufacturers and transport operators to aid them in specifying equipment which would meet requirements for security and passenger flow and at the same time be acceptable, convenient and safe for use by passengers.

Stage one consisted of field studies at three railway stations and a laboratory evaluation of five types of ticket barrier. The field studies were undertaken to record and identify the characteristics of users and the type and frequency of problems they encountered. The laboratory trials consisted of objective and subjective evaluations of the four barriers by selected classes of user. Stage two consisted of a detailed study of certain features of barrier design, identified in stage one, including the type and speed of ticket checking, barrier dimensions and equipment for luggage handling. Results of the research have enabled design recommendations to be drawn up for use in the specification of future ticket barrier design.