The influence of prototype fidelity and aesthetics of design in usability tests: effects on user behaviour, subjective evaluation and emotion

An empirical study examined the impact of prototype fidelity on user behaviour, subjective user evaluation and emotion. The independent factors of prototype fidelity (paper prototype, computer prototype, fully operational appliance) and aesthetics of design (high vs. moderate) were varied in a between-subjects design. The 60 participants of the experiment were asked to complete two typical tasks of mobile phone usage: sending a text message and suppressing a phone number. Both performance data and a number of subjective measures were recorded. The results suggested that task completion time may be overestimated when a computer prototype is being used. Furthermore, users appeared to compensate for deficiencies in aesthetic design by overrating the aesthetic qualities of reduced fidelity prototypes. Finally, user emotions were more positively affected by the operation of the more attractive mobile phone than by the less appealing one.     

单脉冲雷达的波纹波导多模馈源

本文叙述一种用于单脉冲雷达的波纹多模馈源的性能。该馈源用四个方喇叭输出口来激励和模与差模。适当地选择参数能使辐射方向图具有低的交叉极化电平,因而可适应截获目标的极化特性。本文给出了波导不连续性问题的分析结果并讨论了波导模之间相位差的补偿方法。一些初步的实验结果同理论计算相符合。     

A comparison of exact and approximate adjoint sensitivities in fluorescence tomography

Many approaches to fluorescence tomography utilize some form of regularized nonlinear least-squares algorithm for data inversion, thus requiring repeated computation of the Jacobian sensitivity matrix relating changes in observable quantities, such as emission fluence, to changes in underlying optical parameters, such as fluorescence absorption. An exact adjoint formulation of these sensitivities comprises three terms, reflecting the individual contributions of 1) sensitivities of diffusion and decay coefficients at the emission wavelength, 2) sensitivities of diffusion and decay coefficients at the excitation wavelength, and 3) sensitivity of the emission source term. Simplifying linearity assumptions are computationally attractive in that they cause the first and second terms to drop out of the formulation. The relative importance of the three terms is thus explored in order to determine the extent to which these approximations introduce error. Computational experiments show that, while the third term of the sensitivity matrix has the largest magnitude, the second term becomes increasingly significant as target fluorophore concentration or volume increases. Image reconstructions from experimental data confirm that neglecting the second term results in overestimation of sensitivities and consequently overestimation of the value and volume of the fluorescent target, whereas contributions of the first term are so low that they are probably not worth the additional computational costs.     

Impact of additive noise on system performance of a digital X-ray imaging system

The impact of additive noise on the performance of a digital X-ray imaging system was investigated. The X-ray system is uniquely designed for small animal studies with a focal spot of 20 microm and an adjustable source-to-object distance for radiography. The noise power spectrum and the detective quantum efficiency of this system were measured. The additive noise increased rapidly when the exposure time exceeded a certain range, since the charge-coupled devices of the detector had no cooling system. The noise power spectrum for the additive noise and the noise of the entire imaging system were studied and compared at different exposure times. The detective quantum efficiency was also measured at different exposure times. It was observed that for exposure times less than 10 s, the detective quantum efficiency ((DQE)(0)) is approximately 0.26, dropping to 0.13 at 4 lp/mm and to 0.026 at 8 lp/mm. However, when the exposure exceeds a certain limit (10 s in this study), the rapidly increased additive noise caused the system to be no longer quantum noise limited, resulting in a decreased detective quantum efficiency and a degraded system performance. For example, at an exposure of 20 s, the DQE(O) is approximately 0.22, dropping to 0.11 at 3 lp/mm and to 0.022 at 8 lp/mm.     

Comparison of entropy and complexity measures for the assessment of depth of sedation

Entropy and complexity of the electroencephalogram (EEG) have recently been proposed as measures of depth of anesthesia and sedation. Using surrogate data of predefined spectrum and probability distribution we show that the various algorithms used for the calculation of entropy and complexity actually measure different properties of the signal. The tested methods, Shannon entropy (ShEn), spectral entropy, approximate entropy (ApEn), Lempel-Ziv complexity (LZC), and Higuchi fractal dimension (HFD) are then applied to the EEG signal recorded during sedation in the intensive care unit (ICU). It is shown that the applied measures behave in a different manner when compared to clinical depth of sedation score--the Ramsay score. ShEn tends to increase while the other tested measures decrease with deepening sedation. ApEn, LZC, and HFD are highly sensitive to the presence of high-frequency components in the EEG signal.     

Fluorescent protein tomography scanner for small animal imaging

Microscopy of fluorescent proteins has enabled unprecedented insights into visualizing gene expression in living systems. Imaging deeper into animals, however, has been limited due to the lack of accurate imaging methods for the visible. We present a novel system designed to perform tomographic imaging of fluorescent proteins through whole animals. The tomographic method employed a multiangle, multiprojection illumination scheme, while detection was achieved using a highly sensitive charge-coupled device camera with appropriate filters. Light propagation was modeled using a modified solution to the diffusion equation to account for the high absorption and high scattering of tissue at the visible wavelengths. We show that the technique can quantitatively detect fluorescence with sub millimeter spatial resolution both in phantoms and in tissues. We conclude that the method could be applied in tomographic imaging of fluorescent proteins for in vivo targeting of different diseases and abnormalities.     

湿热气候条件下砌体结构材料热湿物性参数对热工计算的影响

针对湿热气候地区高湿度对砌体结构隔热的不利影响,利用计算机软件模拟四种不同砌体结构材料热湿物性参数：导热系数、蒸汽渗透系数和液态水扩散系数在动态热湿环境下的变化,从而分析热湿物性参数变化对建筑围护结构热工计算的影响程度.结果表明：在湿热气候条件下,湿传递对热工计算结果的影响较大,传热量最多增加30%;导热系数变化对传热量影响的幅度在5%～10%;蒸汽渗透系数变化对传热量影响在3%以下;液态水渗透系数受室外计算条件影响,非雨天时,其值变化对传热量计算不大,雨天时,其值变化对传热量影响在30%以上.因此,在湿热气候条件下,进行砌体结构围护结构的热工计算时,导热系数应视为材料含湿量的函数计算,蒸汽渗透系数可按常数计算,液态水扩散系数需要考虑雨天和非雨天分别进行计算.     

Performance characteristics of a compact position-sensitive LSO detector module

We assembled a compact detector module comprised of an array of small, individual crystals of lutetium oxyorthosilicate:Ce (LSO) coupled directly to a miniature, metal-can, position-sensitive photomultiplier tube (PSPMT). We exposed this module to sources of 511-keV annihilation radiation and beams of 30- and 140-keV photons and measured spatial linearity; spatial variations in module gain, energy resolution, and event positioning; coincidence timing; the accuracy and sensitivity of identifying the crystal-of-first-interaction at 511 keV; and the effects of intercrystal scatter and LSO background radioactivity. The results suggest that this scintillator/phototube combination should be highly effective in the coincidence mode and can be used, with some limitations, to image relatively low-energy single photon emitters. Photons that are completely absorbed on their first interaction at 511 keV are positioned by the module at the center of a crystal. Intercrystal scatter events, even those that lead to total absorption of the incident photon, are placed by the module in a regular "connect-the-dot" pattern that joins crystal centers. As a result, the accuracy of event positioning can be made to exceed 90%, though at significantly reduced sensitivity, by retaining only events that occur within small regions-of-interest around each crystal center and rejecting events that occur outside these regions in the connect-the-dot pattern.     

FBG Temperature and Pressure Sensing System for Hot Water Pipeline of Petrochemical Factory

A spatial and wavelength division multi- plexing fiber Bragg grating （FBG） sensing system is reported for monitoring the temperature and the pressure （T-P） of hot water pipeline in petrochemieal factory. The FBG sensing system has 72 channels independently, and it provides the capability to monitor large number sensors at same time. A resolution of 0.1℃ and 0.01 MPa with a measurement bandwidth of 150 Hz has been achieved.     

Status and Trends in Advanced SOI Devices and Materials

提供了一种用于安德鲁反射测量样品制备新方法.该方法采用聚焦粒子束刻蚀和磁控溅射,可以获得可控的、干净的、无应力的纳米接触用于自旋极化探测.所制备的样品中,磁性和非磁性材料样品的反射谱都表现出复杂的峰和谷结构,这些结构可能源于与界面相关的零偏压反常以及与激发态相关的准离子相互作用.对另一个Co40Fe40B20合金样品采用简单的钕针尖压针方法进行了对比性测量,反射谱中没有观察到谷结构,但谱结构出现较明显的热扩展,这种热扩展可能来源于界面处的非弹性输运.所有的反射谱目前还不能由现有的理论给出令人满意的解释.利用点接触反射方法获得可靠的自旋极化信息还有赖于接触界面特征的进一步分析.而一个更切合实际的、更完善的理论成为迫切的需要.