A new prototype of self-pressurizing fuel tank for micro and nano-satellites

To increase effective load, light-weight micro-propulsion system is necessary for micro-satellites. Traditional propulsion systems including large and heavy high-pressure vessels are difficult to be scaled down to fulfill the demand of micro-satellites. In this article, a novel self-pressurizing fuel tank without high-pressure gas vessel is proposed. When some liquid propellant is consumed, pressure is compensated with CO2 released by heating NH4HCO3 powder in the fuel tank. Comparing with other types of self-pressurizing liquid fuel tank, a gas generator with special and simple structure was designed to stop or continue the NH4HCO3 decomposition reaction easily, and consumed a small amount of energy to heat the powder effectively. Performance tests showed that this new prototype is very suitable for micro-thrusters.

一种水面救助机器人

本文介绍一种能在恶劣海况下 ,向遇险船舶送递导引缆绳和向落水人员快速送递救生圈的水面救助机器人 .该机器人具有抗涌浪能力强、体积小、重量轻、速度快以及机动灵活的特点 ,还可广泛应用于其他领域

谐波驱动系统的特性及控制策略研究

谐波传动有很多优点，在机器人驱动中经常被使用．但谐波传动也有一些缺点，如柔性等因素影响负载端轨迹跟踪精度．本文系统地分析了谐波传动系统的动力学特性，建立了包括电机转子惯量在内的动力学模型，疽对系统进行全面实验研究的基础上总结出谐波传动系统中存在的问题，采用相应的基于传感器的控制策略克服存在的问题，提高系统的响应性能．从理论分析和实验结果证实了提出方法的可行性。

Portable, Fiber-Based, Diffuse Reflection Spectroscopy (DRS) Systems for Estimating Tissue Optical Properties.

Steady-state diffuse reflection spectroscopy is a well-studied optical technique that can provide a noninvasive and quantitative method for characterizing the absorption and scattering properties of biological tissues. Here, we compare three fiber-based diffuse reflection spectroscopy systems that were assembled to create a light-weight, portable, and robust optical spectrometer that could be easily translated for repeated and reliable use in mobile settings. The three systems were built using a broadband light source and a compact, commercially available spectrograph. We tested two different light sources and two spectrographs (manufactured by two different vendors). The assembled systems were characterized by their signal-to-noise ratios, the source-intensity drifts, and detector linearity. We quantified the performance of these instruments in extracting optical properties from diffuse reflectance spectra in tissue-mimicking liquid phantoms with well-controlled optical absorption and scattering coefficients. We show that all assembled systems were able to extract the optical absorption and scattering properties with errors less than 10%, while providing greater than ten-fold decrease in footprint and cost (relative to a previously well-characterized and widely used commercial system). Finally, we demonstrate the use of these small systems to measure optical biomarkers in vivo in a small-animal model cancer therapy study. We show that optical measurements from the simple portable system provide estimates of tumor oxygen saturation similar to those detected using the commercial system in murine tumor models of head and neck cancer.

The Paralax Infrastructure: Automatic Parallelization With a Helping Hand

Speeding up sequential programs on multicores is a challenging problem that is in urgent need of a solution. Automatic parallelization of irregular pointer-intensive codes, exempli?ed by the SPECint codes, is a very hard problem. This paper shows that, with a helping hand, such auto-parallelization is possible and fruitful. This paper makes the following contributions: (i) A compiler framework for extracting pipeline-like parallelism from outer program loops is presented. (ii) Using a light-weight programming model based on annotations, the programmer helps the compiler to ?nd thread-level parallelism. Each of the annotations speci?es only a small piece of semantic information that compiler analysis misses, e.g. stating that a variable is dead at a certain program point. The annotations are designed such that correctness is easily veri?ed. Furthermore, we present a tool for suggesting annotations to the programmer. (iii) The methodology is applied to autoparallelize several SPECint benchmarks. For the benchmark with most parallelism (hmmer), we obtain a scalable 7-fold speedup on an AMD quad-core dual processor. The annotations constitute a parallel programming model that relies extensively on a sequential program representation. Hereby, the complexity of debugging is not increased and it does not obscure the source code. These properties could prove valuable to increase the ef?ciency of parallel programming.

Development of a Portable Tissue Micro Array Instrument

Tissue micro array (TMA) is based on the idea of applying miniaturization and a high throughput approach to hybridization-based analyses of tissues. It facilitates biomedical research on a large scale in a single experiment; thus representing one of the most commonly used technologies in translational research. A critical analysis of the existing TMA instruments indicates that there are potential constraints in terms of portability, apart from costs and complexity. This paper will present the development of an affordable, configurable, and portable TMA instrument to allow an efficient collection of tissues, especially in instrument-to-tissue scenarios. The purely mechanical instrument requires no energy sources other than the user, is light weight, portable, and simple to use. [DOI: 10.1115/1.4004922]

Conducting Polyaniline Composites as Microwave Absorbers

Conducting polymers are excellent microwave absorbers and they show technological advantage when compared with inorganic electromagnetic absorbing materials, being light weight , easily processable, and the ability of changing the electromagnetic properties with nature and amount of dopants, synthesis conditions, etc. In this paper we report the synthesis, dielectric properties, and expected application of conducting composites based on polyaniline (PAN). Cyclohexanone soluble conducting PAN composites of microwave conductivity 12.5 S/m was synthesized by the in situ polymerization of aniline in the presence of emulsion grade polyvinyl chloride. The dielectric properties of the composites, especially the dielectric loss, conductivity, dielectric heating coefficient , absorption coefficient, and penetration depth, were studied using a HP8510 vector network analyzer. The microwave absorption of the composites were studied at different frequency bands i.e, S, C, and X bands (2-12 GHz). The absorption coefficient was found to be higher than 200 m -' and it can be used for making microwave absorbers in space applications .

Conducting Polyaniline Composites as Microwave Absorbers

Conducting polymers are excellent microwave absorbers and they show technological advantage when compared with inorganic electromagnetic absorbing materials, being light weight , easily processable, and the ability of changing the electromagnetic properties with nature and amount of dopants, synthesis conditions, etc. In this paper we report the synthesis, dielectric properties, and expected application of conducting composites based on polyaniline (PAN). Cyclohexanone soluble conducting PAN composites of microwave conductivity 12.5 S/m was synthesized by the in situ polymerization of aniline in the presence of emulsion grade polyvinyl chloride. The dielectric properties of the composites, especially the dielectric loss, conductivity, dielectric heating coefficient , absorption coefficient, and penetration depth, were studied using a HP8510 vector network analyzer. The microwave absorption of the composites were studied at different frequency bands i.e, S, C, and X bands (2-12 GHz). The absorption coefficient was found to be higher than 200 m -' and it can be used for making microwave absorbers in space applications

“Fabrication and characterization of polymer optical fibers for photonic device applications

Although the main application of optical fibers are in the field of telecommunication, optical fiber based sensors of various designs are becoming valuable devices for wide industrial applications. The advantages of optical fiber-based sensors include high sensitivity, insensitivity to electromagnetic radiation; spark free, light weight and minimal intrusiveness due to their relatively small size and deployment in harsh and hostile environments. It has been proved that POI-7 based sensors can be employed to detect a great variety of parameters including temperature, humidity, pressure, refractive index etc. The proposed thesis presented in six chapters deals with the work carried on dye doped and undoped POF for photonic device applications such as amplifier, laser and sensor

Ni filled flexible multi-walled carbon nanotube–polystyrene composite films as efficient microwave absorbers

In this letter, we report flexible, non corrosive, and light weight nickel nanoparticle@multi-walled carbon nanotube–polystyrene (Ni@MWCNT/PS) composite films as microwave absorbing material in the frequency range of S band (2-4 GHz). Dielectric permittivity and magnetic permeability of composites having 0.5 and 1.5 wt. % filler amount were measured using the cavity perturbation technique. Reflection loss maxima of 33 dB (at 2.7 GHz) and 24 dB (at 2.7 GHz) were achieved for 0.5 and 1.5 wt. % Ni@MWCNT/PS composite films of 6 and 4 mm thickness, respectively, suggesting that low concentrations of filler provide significant electromagnetic interference shielding

Performance Assessment of Sandwich Structures with Debonds and Dents

A sandwich construction is a special form of the laminated composite consisting of light weight core, sandwiched between two stiff thin face sheets. Due to high stiffness to weight ratio, sandwich construction is widely adopted in aerospace industries. As a process dependent bonded structure, the most severe defects associated with sandwich construction are debond (skin core bond failure) and dent (locally deformed skin associated with core crushing). Reasons for debond may be attributed to initial manufacturing flaws or in service loads and dent can be caused by tool drops or impacts by foreign objects. This paper presents an evaluation on the performance of honeycomb sandwich cantilever beam with the presence of debond or dent, using layered finite element models. Dent is idealized by accounting core crushing in the core thickness along with the eccentricity of the skin. Debond is idealized using multilaminate modeling at debond location with contact element between the laminates. Vibration and buckling behavior of metallic honeycomb sandwich beam with and without damage are carried out. Buckling load factor, natural frequency, mode shape and modal strain energy are evaluated using finite element package ANSYS 13.0. Study shows that debond affect the performance of the structure more severely than dent. Reduction in the fundamental frequencies due to the presence of dent or debond is not significant for the case considered. But the debond reduces the buckling load factor significantly. Dent of size 8-20% of core thickness shows 13% reduction in buckling load capacity of the sandwich column. But debond of the same size reduced the buckling load capacity by about 90%. This underscores the importance of detecting these damages in the initiation level itself to avoid catastrophic failures. Influence of the damages on fundamental frequencies, mode shape and modal strain energy are examined. Effectiveness of these parameters as a damage detection tool for sandwich structure is also assessed

Embodiment and Manipulation Learning Process for a Humanoid Hand

Babies are born with simple manipulation capabilities such as reflexes to perceived stimuli. Initial discoveries by babies are accidental until they become coordinated and curious enough to actively investigate their surroundings. This thesis explores the development of such primitive learning systems using an embodied light-weight hand with three fingers and a thumb. It is self-contained having four motors and 36 exteroceptor and proprioceptor sensors controlled by an on-palm microcontroller. Primitive manipulation is learned from sensory inputs using competitive learning, back-propagation algorithm and reinforcement learning strategies. This hand will be used for a humanoid being developed at the MIT Artificial Intelligence Laboratory.

Herramienta de detección y medición de las condiciones de riesgo laborales asociadas a la presentación de los desórdenes por trauma acumulativo en hombro

El movimiento en el complejo articular de hombro, al igual que en las demás partes del cuerpo se realiza gracias a los sistemas óseo, articular y muscular. Cuando se presentan movimientos repetitivos, posturas y fuerzas en el lugar de trabajo al desarrollar las tareas, se pueden originar una serie de patologías profesionales en los trabajadores ocupacionalmente expuestos. Estas patologías no solamente se asocian a estos factores de riesgo, sino también, a una concepción inadecuada del diseño del puesto de trabajo en dónde los trabajadores desarrollan su actividad laboral. se pretende a través de este proyecto de investigación dar a conocer una herramienta de observación, detección de éstos, y medición tridimensional de los movimientos que puedan llegar a representar un riesgo, facilitando la recolección de datos de forma precisa y rápida, así como la apreciación de las condiciones de trabajo, por parte de los profesionales interesados en Salud Ocupacional.

Grid Remote Execution (G-Rex) of Climate Models

G-Rex is light-weight Java middleware that allows scientific applications deployed on remote computer systems to be launched and controlled as if they are running on the user's own computer. G-Rex is particularly suited to ocean and climate modelling applications because output from the model is transferred back to the user while the run is in progress, which prevents the accumulation of large amounts of data on the remote cluster. The G-Rex server is a RESTful Web application that runs inside a servlet container on the remote system, and the client component is a Java command line program that can easily be incorporated into existing scientific work-flow scripts. The NEMO and POLCOMS ocean models have been deployed as G-Rex services in the NERC Cluster Grid, and G-Rex is the core grid middleware in the GCEP and GCOMS e-science projects.