A systematic spatial bias in remembering eye positions

Categorical bias in location memory in geometric spaces is well established. The present study assessed the presence of the bias in locating eyes in images of human faces. Participants were presented with digital faces and indicated the position of one of the eyes in both upright and inverted orientations. Biases resulted from participants using multiple sources of accessible information. No differences were found for upright vs. inverted face images. Overall, the data were consistent with the retrieval category adjustment model. These distortions may be considered within the forensic context, when eyewitnesses work with a sketch artist or use a computer program to generate an image of the culprit.     

Experimental and numerical investigation on surface quality for two-point incremental sheet forming with interpolator

The unsatisfied surface quality seriously impedes the wide application of incremental sheet forming (ISF) in industrial field. As a novel approach, the interpolator method is a promising strategy to enhance the surface quality in ISF. However, the mechanism for the improvement of surface quality and the influence of interpolator properties on surface roughness are not well understood. In this paper, the influences of process variables (i.e. tool diameter, step size and thickness of interpolators) on the forming process (e.g. surface roughness, forming force and geometric error) are investigated through a systematic experimental approach of central composite design (CCD) in two-point incremental sheet forming (TPIF). It is obtained that the increase in thickness of interpolators decreases the surface roughness in direction vertical to the tool path while increases the surface roughness in direction horizontal to the tool path. Nevertheless, the combined influence between thickness of interpolators and process parameters (tool diameter and step size) is limited. Meanwhile, the placement of interpolator has little influence on the effective forming force of blank. In addition, the geometric error enlarges with the increase of step size and thickness of interpolator while decreases firstly and then increase with an increase in tool diameter. Finally, the influencing mechanism of the interpolator method on surface quality can be attributed to the decrease of the contact pressure due to the increase of contact area with the unchanged contact force. Meanwhile, the interpolator method eliminates the sliding friction on the surface of blank due to the stable relative position between the blank and the interpolator.     

Direct position determination using single moving rotating linear array: Noncoherent and coherent processing

To improve the resolution and accuracy of Direct Position Determination (DPD), this paper investigates the problem of positioning multiple emitters directly with a single moving Rotating Linear Array (RLA). Firstly, the geometry of the RLA is formulated and analysed. According to its geometry, the intercepted noncoherent signals in multiple interception intervals are modeled. Correspondingly, the MUltiple SIgnal Classification (MUSIC) based noncoherent DPD approach is proposed. Secondly, the synchronous coherent pulse signals are individually considered and formulated. And the coherent DPD approach which aims for localizing this special type of signal is presented by stacking all array responses at different interception intervals. Besides, we also derive the constrained Cramér-Rao Lower Bound (CRLB) expression for both noncoherent and coherent DPD with RLA under the constraint that the altitudes of the emitters are known. At last, computer simulations are included to examine the performance of the proposed approach. The results demonstrate that the localization accuracy and resolution of DPD with single moving linear array can be significantly improved by the array rotation. In addition, coherent DPD with RLA further improves the resolution and increases the maximum emitter number that can be localized compared with the noncoherent DPD with RLA.     

高校委托工程审计的质量控制与评价指标体系构建

委托工程审计质量关系到高校工程审计职能的发挥和投资建设目标的实现.结合高校工程审计实践,探讨高校委托工程审计质量控制关键路径,并据此构建质量评价指标体系,以实现高校委托工程审计质量有效控制和科学评价.     

GPS在卫星精密测轨中的应用

自从美国全球定位系统(GPS)试验系统建立以来,发展了各种各样的方法,利用GPS 测量来精密确定卫星轨道。在1984年,LANDSAT-5上装载一个GPSPAC 的仪器进行了飞行,以验证用GPS 定轨的精确度。1982年在美国喷气推进试验室((?)PL),为TOPEX 卫星研究了一种GPS 距离和距离变化率的双差分法,以满足其厘米级的精度要求。除GPS 对低轨地球卫星定轨应用外,有人也提出了用GPS 测量对高轨地球卫星甚至同步卫星的定轨方法及精度分析。文章对上述各种方法给以简要的介绍和评述。     

磁带机运转对星载CCD相机成像的影响

利用Ｌａｇｒａｎｇｅ方程,建立了磁带轮转动和卫星姿态振动相互影响的仿真模型,并用数值计算方法计算了卫星的姿态振动,仿真分析了对星载线阵ＣＣＤ成像质量的影响。     

一种高精度夹具的设计原理

通过对定位精度高达２μｍ,又非常便捷装卸的瑞士ＥＲＯＷＡ夹具结构原理的介绍,以引起国内同行的关注,旨在推广应用于我国航空精密零件及工模具生产中,以期解决长期困惑我国的高位置精度问题。     

激光辅助车削工艺参数对单晶硅表面质量的影响

为了提高单晶硅激光辅助车削加工表面质量,通过开展激光辅助和常规车削加工试验,结合表面粗糙度、表面形貌及拉曼光谱检测,研究激光辅助车削技术对加工质量的影响。基于正交试验方法,研究单晶硅激光辅助车削工艺参数对表面粗糙度的影响;通过方差分析和极差分析评估各因素对表面粗糙度的影响。研究结果表明：与常规车削相比,激光辅助车削可有效提高加工表面质量,降低材料表面的残余应力。主轴转速、进给速度、切削深度和脉冲占空比对表面粗糙度的贡献率分别为17.51%、44.48%、6.69%和14.70%。确定最佳加工参数组合如下：主轴速度为4 000 r/min,进给速度为2 mm/min,切削深度为5μm,脉冲占空比为30%,最终获得表面粗糙度Rq为2.4 nm的高质量表面。     

卫星天线双轴定位机构建模与仿真

卫星天线定位机构对控制天线的运动精确具有重要的意义。本文介绍了卫星点波束天线双轴定位机构的基本组成,建立了刚体动力学模型、仿真模型,并开发了仿真软件,对系统进行了仿真。     

缝纫/RFI层合板单钉连接性能试验研究

通过对不同铺层及不同缝纫角度的缝纫／RFI层合板的单钉单剪连接强度试验,了解到缝纫针脚位置对缝纫层合板机械连接性能有显著的影响。当针脚距离钉孔受挤压边缘较近时,缝纫层合板的挤压破坏强度低于普通的层合板,只有当针脚在钉孔挤压区外或距离钉孔受挤压边缘较远时,缝纫层合板才显示出好于普通层合板的机械连接性能。试验结果还表明铺层比对缝纫层合板的机械连接性能也有影响,其规律类似于普通层合板。