A Spatial Audio System Using Multiple Microphones on a Rigid Sphere

The main purpose of a spatial audio system is to give a listener the same impression as if he/she were present in a recorded environment. A dummy head microphone is generally used for such purposes. Because of its human‐like shape, we can obtain good spatial sound images. However, its shape is a restriction on its public use and it is difficult to convert a 2‐channel recording into multi‐channel signals for an efficient rendering over a multi‐speaker arrangement. In order to solve the problems mentioned above, a spatial audio system is proposed that uses multiple microphones on a rigid sphere. The system has five microphones placed on special points of the rigid sphere, and it generates audio signals for headphone, stereo, stereo dipole, 4‐channel, and 5‐channel reproduction environments. Subjective localization experiments show that front/back confusion, which is a common limitation of spatial audio systems using the dummy head microphone, can be reduced dramatically in 4‐channel and 5‐channel reproduction environments and can be reduced slightly in a headphone reproduction     

轴端球头加工方法研究

轴端球头类零件在普通机床上直接加工比较困难．根据球面的特点，将普通机床稍加改造，可以方便地实现球头类零件的加工．     

Modelling percolation in fibre and sphere mixtures: Routes to more efficient network formation

Mixtures of perfectly conducting fibres and spheres, as well as mixtures of fibres of different aspect ratios, were simulated using a Dissipative Particle Dynamics (DPD) method, and the connectivity of the resulting assemblies was analysed using a Monte Carlo algorithm to predict the threshold volume fraction of filler material required for electrical percolation. For both isotropic and uniaxially oriented fibre–sphere mixtures, it was found that gradually replacing fibres with an equivalent volume of spheres increased the percolation threshold. By contrast, in aligned mixtures of fibres of two different aspect ratios, replacing a small fraction of higher aspect ratio fibres with shorter fibres led to a reduction in the percolation threshold, since the shorter fibres orient less well and provide bridging links between the highly oriented longer fibres. These theoretical results suggest that mixtures of fibres of different aspect ratio may be helpful in reducing the volume fraction of high aspect ratio filler particles (such as multi-wall carbon nanotubes) required to achieve significant electrical conductivity in composite materials.     

汽油车差速器壳内球面加工工装设计

为CA1 0 4 6L型差速器壳内球面加工设计了专用工装 ,并进行了分析和论证。     

Freezing of tilapia fillets in an air blast freezer

This paper explores the numerical simulation of freezing tilapia fillets of five different geometries, which are the slab, elliptical, disc, spherical and cylindrical shapes, in an air blast freezer. The air velocities and temperatures inside the freezer are varied in the simulation to determine the freezing times and energy consumptions for freezing the tilapia fillets of different shapes. The results show that the cylindrical-shaped fillet has the longest freezing time and also required the most energy for freezing. The slab-shaped fillet has the shortest freezing time, but the spherical-shaped fillet requires the least energy to freeze. The simulation is also applied to a case study to compare the processing rate, energy consumption and the cost of freezing the fillets of different shapes. The freezing cost for a tray of spherical-shaped fillet is the lowest among all.     

微波辅助polyol法制备的纳米镍颗粒

采用微波辅助polyol还原法制备了单分散的纳米Ni颗粒。分别用X射线衍射(XRD)和透射电镜(TEM)观测样品的相结构和微观形貌,用振动样品磁强计(VSM)测试Ni颗粒的磁性。XRD显示样品为面心立方结构,TEM观察显示金属镍颗粒的形貌是理想的球型。当把反应温度提高到400℃,并且在实验过程中加入适量的PVP时,发现镍颗粒呈现出一种毛茸茸的多毛形态,这种分散均匀的单一态形貌类似于纳米头发的结构。同时,VSM测试结果表明球型纳米Ni颗粒具有典型的铁磁性。     

Experimental investigation of burning rates of pure ethanol and ethanol blended fuels

A fundamental experimental study to determine the burning rates of ethanol and ethanol-blended fossil fuels is presented. Pure liquid ethanol or its blends with liquid fossil fuels such as gasoline or diesel, has been transpired to the surface a porous sphere using an infusion pump. Burning of the fuel takes place on the surface of the porous sphere, which is placed in an air stream blowing upwards with a uniform velocity at atmospheric pressure and temperature under normal gravity conditions. At low air velocities, when ignited, a flame envelopes the sphere. For each sphere size, air stream velocity and fuel type, the fuel feed rate will vary and the same is recorded as the burning rate for that configuration. The flame stand-off distances from the sphere surface are measured by post-processing the digital image of the flame photograph using suitable imaging software. The transition velocity at which the flame moves and establishes itself at the wake region of the sphere has been determined for different diameters and fuel types. Correlations of these parameters are also presented.     

侧钻井投球调剖技术室内模拟及方案设计

为解决侧钻井转注水后分层注水难度大的问题,将投球调剖技术应用到侧钻井注水中,实现资源的重新利用.介绍了投球调剖技术的工作原理和技术优点,阐述了调剖球的性能特征,通过实验室建立侧钻井仿真可视模型的方式,进行了侧钻井中投球调剖的物理模拟实验.实验验证了调剖球在侧钻井中封堵的可行性,依据大量数据分析了调剖球封堵炮眼的规律,确定了不同工况下投球位置、井筒内流量对封堵效果的影响.提出了靠近目标层投球和适当控制流量的方法,该方法可实现对调剖球在井筒中运动的控制,给出了不同注入位置及各层流量比下最优的投球方式、流量大小和投球数量,为现场施工提供了参考依据.     

Microstructure of Yolk from Fresh Eggs by Improved Method

Methods were examined to fix hen's egg yolk while retaining its original sol structure and to elucidate the fine structure of fresh yolk by using the freeze-cutting fixation method with liquid nitrogen. In fresh native yolk, histological differences were observed in the yolk spheres in each layer and latebra part. These spheres were closely packed in the vitelline membrane, with various sizes and shapes. Protein granules with high electron density were noted in the yolk sphere and their distribution and shape differed between the outer and inner layers.