电制冷Si-PIN X射线谱仪的研制

X射线谱仪以其多用途、无损、操作简单、快速、价格低廉和运行费用很低等优点，己经成为应用最为广泛的多元素分析仪器。采用液氮冷却的X射线谱仪在荧光分析技术领域得到广泛的应用和普遍认可。液氮制冷的一个主要缺点是必须有一个液氮存储罐作为完整谱仪的一部分。从而，在实际应用中受到液氮价格贵和液氮供应厂少的限制，大大地制约了该种谱仪的进一步推广使用。如果能采用另外的技术得到足够低的温度，在此温度下探测器具有极低的漏电流，也可使X射线谱仪有极低的噪声和相当好的能量分辨率；因此克服上述限制就成为一个有重要意义的课题方向。本文在国内首次实现采用半导体电制冷技术对平面离子注入（Si一PIN）探测器制冷，降低探测器漏电流至10~(-13)以下，配合低噪声脉冲光反馈前放，成功地使得整个x射线谱仪能量分辨率达到262eV（对~(55)Fe的Mn Kα K射线）。虽然电制冷X射线谱仪的分辨率没有采用液氮冷却的好，但是它的性能已足够在包括利用X射线能量分离进行荧光分析等多种应用所需。考虑到元素周期表中钾元素以上的毗邻两元素的Ka特征X射线的能量差在380eV以上；例如，K和Ca的峰线宽分别是243eV和245 eV，由此得到电制冷X射线谱仪己可完成对K, C a和更高Z的元素进行能散荧光分析工作。并且，液氮罐的取消可方便的设计在野外使用的便携式X射线荧光分析设备。 文中全面介绍了X射线谱仪的各个组成部分和其背景知识。并详细描述了探测器系统、电制冷系统和低噪声电子学系统，充分展示了研制X射线谱仪的关键所在。最后给出了电制冷X射线谱仪的测试结果和应用设计。

Physical modelling of millimetre wave signal reflection from forward biased PIN diodes

This paper examines the DC power requirements of PIN diodes which, with suitable applied DC bias, have the potential to reflect or to permit transmission of millimetre wave energy through them by the process of inducing a semiconductor plasma layer in the i-region. The study is conducted using device level simulation of SOI and bulk PIN diodes and reflection modelling based on the Drude conduction model. We examined five diode lengths (60–140 µm) and seven diode thicknesses (4–100 µm). Simulation output for the diodes of varying thicknesses was subsequently used in reflection modelling to assess their performance for 100 GHz operation. It is shown that substantially high DC input power is required in order to induce near total reflection in SOI PIN diodes at 100 GHz. Thinner devices consume less DC power, but reflect less incident radiation for given input power. SOI diodes are shown to have improved carrier confinement compared with bulk diodes.

Numerical Investigation of Optimal Pin Actuator Location on a Supersonic Projectile

The flowfield around a supersonic projectile using a pin actuator control method has been predicted using computational fluid dynamics. It has been predicted using both viscous and inviscid methods for a number of positions. Both methods showed that an optimal longitudinal position exists. However, the inviscid model over-predicted the lateral acceleration due to the difference in shock formation around the pin between the two approaches. The optimal location was predicted independent of solver, however the higher-fidelity solver predicted lower achievable lateral accelerations. This is due to the viscous interactions caused by the pin. The effect of projectile orientation has shown that shielding the pin leads to reduced effectiveness due to the wake of the fin enveloping the pin. When the pin is exposed to onset flow, the forces achieved are increased. There is also an increase in the achievable forces and moments with increasing Mach number.

3D Analysis of Heat Transfer Intensification by Re-Entrance Flow Pin-Fins Microstructures with a Highly Thermal-Conductive Plate

Joule heat-induced hot-spot formation sets severe limits in the operation of continuous annular electrochromatography (CAEC), a new concept for preparative separation as an analog to analytical capillary electrochromatography (CEC). This may lead to eluent flow perturbance, even to boiling, which would massively weaken separation efficiency and may even hamper the stationary phase used for separation. For reasons of system integration and high-efficiency heat transfer, micro flow heat exchangers are considered with a separate coolant flow. A 3D numerical analysis of the heat transfer of water single-phase laminar flow in a square microchannel and different arrays of micro pin-fins was carried out using COMSOL Multiphysics. Several advanced materials with low electric conductivity and at the same time with high heat conductivity were put forward to be used in the CAEC system. As essential design point, it is proposed to constitute the micro heat exchanger from two different parts of the CAEC system, namely a microstructured pin-fins plate and a so-called conductive plate.

PROSTATIC INTRAEPITHELIAL NEOPLASIA (PIN) - PERFORMANCE OF BAYESIAN BELIEF NETWORK FOR DIAGNOSIS AND GRADING

Prostatic intraepithelial neoplasia (PIN) diagnosis and grading are affected by uncertainties which arise from the fact that almost all knowledge of PIN histopathology is expressed in concepts, descriptive linguistic terms, and words. A Bayesian belief network (BBN) was therefore used to reduce the problem of uncertainty in diagnostic clue assessment, while still considering the dependences between elements in the reasoning sequence. A shallow network was used with an open-tree topology, with eight first-level descendant nodes for the diagnostic clues (evidence nodes), each independently linked by a conditional probability matrix to a root node containing the diagnostic alternatives (decision node). One of the evidence nodes was based on the tissue architecture and the others were based on cell features. The system was designed to be interactive, in that the histopathologist entered evidence into the network in the form of likelihood ratios for outcomes at each evidence node. The efficiency of the network was tested on a series of 110 prostate specimens, subdivided as follows: 22 cases of non-neoplastic prostate or benign prostatic tissue (NP), 22 PINs of low grade (PINlow), 22 PINs of high grade (PINhigh), 22 prostatic adenocarcinomas with cribriform pattern (PACcri), and 22 prostatic adenocarcinomas with large acinar pattern (PAClgac). The results obtained in the benign and malignant categories showed that the belief for the diagnostic alternatives is very high, the values being in general more than 0.8 and often close to 1.0. When considering the PIN lesions, the network classified and graded most of the cases with high certainty. However, there were some cases which showed values less than 0.8 (13 cases out of 44), thus indicating that there are situations in which the feature changes are intermediate between contiguous categories or grades. Discrepancy between morphological grading and the BBN results was observed in four out of 44 PIN cases: one PINlow was classified as PINhigh and three PINhigh were classified as PINlow. In conclusion, the network can grade PlN lesions and differentiate them from other prostate lesions with certainty. In particular, it offers a descriptive classifier which is readily implemented and which allows the use of linguistic, fuzzy variables.

Numerical analysis of impact events in a centrifugal impact pin mill

Milling is an important operation in many industries, such as mining and pharmaceutical. Although the comminution process during milling has been extensively studied, the material fragmentation mechanisms in a mill are still not well understood partly because of the lack of an understanding on the local stressing and dynamic information under operational conditions in mills. This paper presents a DEM simulation of particle dynamics and impact events in a centrifugal impact pin mill. The main focus is the statistical characteristics of the dominant stressing modes during the milling process. The frequency, velocity and force of the different impact events between particles and mill components, or between particles, are analysed. © 2013 AIP Publishing LLC.

Histoire de Philippe de Madien, par Perrinet DU PIN.

Contient : Table des chapitres, incomplète, et s'arrêtant au chapitre XXII ; Épître dédicatoire de « Perrinet DU PIN, natif de la ville de La Rochelle, ou rouyaume de France », à « Anne de [Lusignan], fille de [Jean II], roy de Cypre, duchesse de Savoie [par son mariage avec le duc Louis] », etc ; Début du premier chapitre : « Quant Regnault de Madien oult demouré avecques le père de sa femme environ XX ans... » ; « ... ainssy que nous raconte l'ystore dudict roy Philipe, lequel en ma conscience je ay extraict, sans riens y mectre et adjouster, fors la vraye vérité, de ce que je ay trouvé ès livres dessudictz, lesquels en faisant la conclusion de cest présent volume ou traictié, je parachevay de veoir et visiter le VIIIe jour du moys de juillet mil CCCC quarante huit. Amen. Explicit »