Recent Patents on Mechanical Engineering - Volume 5, Issue 1, 2012

Recent Patents on Mechanical Engineering is entering into its fifth volume in 2012. We are publishing articles in various disciplines of mechanical engineering i.e. analytical methods, designs, manufacturing, industrial instruments, mechanical properties, machines, heating and cooling systems, automobiles and industrial processes etc. We will be covering below subject areas in this January issue 2012 of Recent Patents on Mechanical Engineering. Sridhar has thoroughly reviewed the developments in the field of thermometry in the last twenty five years. The physical aspects of different technologies depending on temperature measurement methods as well as its applications in various fields' i.e. engineering, atmospheric sciences, biomedicine, military research and related disciplines are comprehensively discussed. Comparative studies of different thermometry systems are given in this article. Theoretic physical principles and developments in radiation thermometry, luminescence thermometry, biomedical thermometry, optical thermometry, thermo-chromic semiconductor thermometry, nano-particle fluorescence thermometry, specular reflection optical band-gap thermometry, antistokes scattering thermometry, acoustic thermometry, ferroelectric thermometry, micro- scale thermometry, interstellar thermometry, fuel cell thermometry have been covered by the author. Malen et al. have recently published an article on optical measurement of thermal conductivity of thin films using fiber aligned frequency domain thermoreflectance (FAFDTR) for different materials [1]. The estimation of fluorescence thermometry (FT) for determining wall surface and bulk fluid temperatures was studied by Kim & Yoda. The factors for increasing the accuracy of fluorescence thermometry and temperature measurements were controlled by taking the ratio of emission signals from fluorophores, fluorescein and sulforhodamine B based on using evanescent-wave illumination [2]. US8016757discloses calibrating methods for temperature estimation technique in biological tissue heat transfer model using backscattered ultrasound data [3]. Microwave sensors measure a temperature of the patient and transmission of the high frequency pulses by magnetic resonance tomography device. Similarly, the invention reported the methods for the measurement of temperature using the fluorescent material through fluorescent temperature sensor [4].The components of Fluorescence Based Thermometry are discussed in WO2011127250.Temperature sensor comprises of fluorescent element from photon source component, temperature measurement probe and signal processing circuit [5]. Another invention relates methods and systems to the radiation sensor used in thermometry for measuring temperature of human body [6]. Mekid presented in his article recent patents on tension monitoring devices for the bolt joints. The recent developments in the bolt joints facilitate the fastener tension in visual and remote inspections. The author has proposed the features of smart bolts to overcome the disasters in industrial plants resulted from bolt losing and insufficient preload issues. Vibration, thermal effects and change in the characteristic of materials are some of the factors considered in bolt failure due to loss of tension. Static mechanical properties of the bolted flange using a simplified nonlinear dynamic model with bi-linear springs was proposed for the analysis of pipe structures. Physical experiments and numerical simulations are performed to confirm coupling vibration behavior [7]. The utilization of an embedded carbon nanotube network in the health monitoring of mechanically fastened cross-ply composites were studied by Thostenson et al. The conductivity of bolted composite joints is modified using an embedded carbon nanotube network and providing evidences for the damage and type of damage which occurs during tensile loading [8]. Feraboli et al. discussed the usage of novel Wireless Identification and Sensing Platform s/g (WISP for strain gage) for performing uniaxial tension tests during static airframe tests and on-board real-time strain measurements on carbon fiber composite specimens during test flights and validation of new aircraft. This device has been used to compare accuracy and repeatability with conventional wired strain gage and extensometer [9]. Stojkov et al. in recent invention describes various designs for bolted joint assembly. The claims in this patent discuss a design which can resist higher threshold force as a bolt is fastened through the reinforcement member and the nut [10]. Robust control of High Precision Positioning System (HPPS) was studied by Raafat et al. The robust adaptive mode control (ARC), adaptive sliding mode control, nominal characteristic trajectory following control(NCTF), robust cross coupled based control (CCC), iterative learning control (ILC), robust controller applications and intelligent techniques based on robust controller, techniques, methodology and approaches and recent patents associated with these techniques were discussed in this article. The review covered the literature published in the last two decades. Some basic types of servomotors used in precision positioning system were also reviewed.

Thermometry plays an extremely important role in engineering and basic sciences. Accurate measurements of temperature are vital for: (a) improving our understanding of various physical phenomena; (b) process control and optimization; (c) determination of material properties; and (d) energy conservation. This review highlights some of the developments that have occurred in thermometry during the period 1984 to 2011. The ensuing discussions focus on the physical principles that have been exploited for the purpose of thermometry. The developments mentioned in this review offer a peek into the past 27 years of thermometry research that has produced several innovations based upon optical refraction, luminescence, fluorescence, thermo-reflectance, color change, radiation, ferro-electricity, acoustic resonance, Raman Effect, and magnetic resonance principles, to name a few. In tune with the emergent interest in micro/nano-scale interdisciplinary technologies, automated high-speed manufacturing processes, and advances in medical engineering, many of the patents reviewed here relate to thermometry for specialized applications. A sizeable majority of these novel arrangements are non-intrusive and non-contact in nature, suitable for remote measurements. Developments on contact-type temperature sensors, that may require invasive techniques and arrangements, are also presented.

The present paper reviews recent patents disclosing various ways to monitor the variation of the bolt tension in order to timely readjust the torque to initial specifications. The recent advances related to bolted joints have seen tremendous developments to ease inspection of the fastening tension in both visual and remote inspections. Precision of bolt tightening is one of the major issues noted in industrial plants where accurate preload is questioned whether it is achieved or not. Insufficient preload, caused by an inaccurate tightening method, is a frequent cause of bolted joint failure which may lead to potentially catastrophic structural failures. The loss of tension may occur due to vibration, thermal effects, change in the material characteristics and so on. Reviews of recent related developments are discussed in this paper with proposal of intended features for smart bolts.

A very high accuracy and resolution, stability, and fast response are the requirements of high precision positioning systems (HPPS). Accurate position sensing and feedback control of the motion are key to the successful precision positioning. In this paper, the robust control of HPPS literature published within last two decades is categorized and discussed. The paper also provides detailed technical descriptions on many such novel methods. According to the type of the control methodology applied in the reviewed literature, the paper categorizes them into seven main categories. The purpose is to emphasize the key role of advanced control techniques in improving precision, accuracy, and the speed of operation of these systems. While doing so, the paper also reviews literature on various applications of robust control for HPPS including some recent patents. However, the list of patents reviewed is not the least assumed to be complete or general. Nevertheless, the evolution and trends in the applications of robust control methods are shown. Based on the analysis of the reviewed patents, the expected future developments in this domain are highlighted.

High speed machining (HSM) is a promising technology for drastically increasing productivity and reducing production costs. Development of high speed spindle technology is strategically critical for researchers to implement HSM. High speed spindles are notorious for their sudden catastrophic failures without alarming signs at high speed due to thermal problems. This paper reviews various patents on thermal characteristics and water-cooling system of high speed motorized spindle and, based on the calculation theory of heat conduction, the finite element software was applied in the simulation and analysis of high speed spindle system aimed at dealing with difficulties in calculating the amount of cooling water and measuring the temperature distribution of helical water-cooling system of the high speed spindle. A finite element thermal model is developed to characterize the heat distribution of a high speed motorized spindle, in particular the characterization of helical water-cooling system. The simulation result, experimental validation and sensitivity analysis show that temperature increase could be significantly reduced with the application of helical water cooling system. Based on the simulation analysis, we can predict the temperature distribution and development of helical water-cooling system when the motorized spindle endures various ambient temperatures and reduces the trial modification times of the water-cooling system design to achieve high efficiency and lower manufacturing cost.

Full text available