Optimization of Transducer Location for Novel Non-Intrusive Methodologies of Diagnosis in Diesel Engines

The health monitoring has been studied to ensure integrity of design of engine structure by detection, quantification, and prediction of damages. Early detection of faults may allow the downtime of maintenance to be rescheduled, thus preventing sudden shutdown of machines. In cylinder pressure developed, vibrations and noise emissions data provide a rich source of information about condition of engines. Monitoring of vibrations and noise emissions are novel non-intrusive methodologies for which positioning of various transducers are important issue. The presented work shows applicability of these diagnosis methodologies adopted in case of diesel engines. The effects of changing various fuel injection parameters was analyzed. Scope of using non-intrusive technique has been analyzed by changing locations of microphone. Novelty of this worklies in exploring signal processing methods for various locations around the engine test set up. Various frequency ranges of contributing noise and vibration sources were identified. Time-Frequency analysis showed the onset of various cyclic. Based on the identification of various frequency bands, it is possible to device suitable filters in order to extract more information.     

A Noninvasive, on Wafer Method to Determine the Intrinsic Stress of a Polymer Layer

The method described in this paper allows an investigator to determine the intrinsic stress of a polymer layer in a way that does not result in damage to devices or test structures. The method requires that a small area of the polymer be released from the substrate to form a diaphragm. The diaphragm is stimulated with acoustic white noise and the diaphragm movement is monitored with a laser vibrometer. The first few resonance frequencies of the diaphragm are obtained using a laser vibrometer and then those frequencies are used to calculate the membrane intrinsic bi-axial tension.     

非晶金刚石膜的性能及其应用

非品金刚石薄膜具有超高硬度等一系列优异的特殊性能，为工程界孜孜追求的材料表面镀膜。用百纳科技公司研发制造的过滤阴极真空电弧离子镀膜机镀制的非晶金刚石薄膜，SP^3金刚石结构量≥80％，硬度高，膜／基结合力高，摩擦系数小，耐磨损，耐腐蚀，透光率高，在电子，机械，光学，生物医学上有广泛应用前景。我们已在视窗玻璃，丝锥，模具，硬质合金刀头等产品上成功应用。     

Resonance method for IR sensing

A highly sensitive method for infrared radiation detection based on thermal resonance in an active bolometer is set forth. An active bolometer is a self-oscillating system consisting of an IR-sensitive cell in a feedback circuit of an adjustable proportional controller. The analysis of an active bolometer autonomous (dark) dynamics reveals that with a generalized gain factor A variation the system evolves from relaxation type towards oscillating and self-oscillating type. When A=A_c, where A_c is a critical value of the generalized gain factor A, the steady state loses stability through self-excited thermal oscillations. The resonance in a system weakly perturbed by IR radiation modulated at self-oscillation frequency q₀[1+exp(iω_ct)] is considered. It is shown that in a small precritical vicinity =(A−A_c)/A_c of the gain factor the amplitude of forced thermal oscillations is proportional to q₀/A_c. The D^* calculation reveals that the detection power of a passive (A=0) bolometer increases with feedback introduction by a factor of 1/||. The detection powers of feasible versions of an active bolometer are compared.     

一次教学实验仪器更新的尝试

探讨了教学实验仪器所面临的更新换代的新形势，结合视频光学投影比工主的研制论述更新的原则和方法。     

NATA: 50 years experience with accreditation

 Laboratory accreditation is becoming increasingly accepted around the world as a means of identifying technically competent laboratories. It is also being used as a mechanism for the acceptance of test data both nationally and internationally. The concept and mechanisms of accreditation have been developed over the past 50 years. The first national laboratory accreditation system appeared in Australia in 1947. This organisation, known as the National Association of Testing Authorities (NATA), has since taken a leading role in developing accreditation practices that are now used world-wide in evaluating testing, measurement and calibration laboratories. This paper examines the development of the world's first and largest laboratory accreditation system, and looks at the difficulties and triumphs in gaining acceptance and recognition by government and industry of the benefits of laboratory accreditation. Received: 24 June 1996 Accepted: 25 June 1996     

Development of a Millimeter Wave Compact Equipment for NDT of Materials

We developed a compact equipment working at 94 GHz to replace the commonly used network analyzer for nondestructive testing of materials. The compact equipment was designed to measure the variations in the amplitude and phase of the reflected signal from the material relative to a reference signal. A good accuracy of the amplitude and phase measurement of the equipment was obtained in the confirmative experiments. The distribution of a drop of water in a wood plate is clearly visible in the millimeter wave images obtained by the amplitude and phase measurement.     

Minkowski-type and Alexandrov-Type Theorems for Polyhedral Herissons

Classical H. Minkowski theorems on existence and uniqueness of convex polyhedra with prescribed directions and areas of faces as well as the well-known generalization of H. Minkowski uniqueness theorem due to A.D. Alexandrov are extended to a class of nonconvex polyhedra which are called polyhedral herissons and may be described as polyhedra with injective spherical image.     

一种测定反应体系压力变化的无汞反应动力学装置

测量反应体系压力变化的装置已有报道,但本文装置具有操作方便、记数准确等优点。 1 实 验 1.1 实验原理及试剂 详见文献。 1.2 装置及仪器 本文的无汞动力学测量装置用于乙炔氢氯化均相催化反应力学研究,其组装图如图1所示。     

Controlling the quality of testing

 This article mainly focuses on the testing of products, materials, etc., but the general principles are applicable in a broader perspective. Quality of testing should be judged based on fitness for purpose. This judgement includes both objective and subjective elements. The possibility to make decisions and other professional judgements based on test results alone is discussed and compared with the decisions and judgements being made through the certification and inspection process. Quality, including the uncertainty of the test results, depends on many factors, and in order to make necessary improvements in the testing procedures based on the customers' needs, the right issues should be addressed. The question arises as to whether, in laboratories' quality systems and in the accreditation and certification process, attention is really paid to those factors that are crucial to obtaining reliable results.