Quantifying Dimensional Accuracy of a Mask Projection Micro Stereolithography System

Mask Projection Microstereolithography is capable for fabricating true three-dimensional microparts and hence, holds promise as a potential micro-fabrication process for micro-machine components. In this paper, the Mask Projection Micro-Stereolithography (MPµSLA) system developed at the Rapid Prototyping and Manufacturing Institute at Georgia Institute of Technology is presented. The dimensional accuracy of the system is improved by reducing its process planning errors. To this effect, the MPµSLA process is mathematically modeled. In this paper, the irradiance received by the resin surface is modeled as a function of the imaging system parameters and the pattern displayed on the dynamic mask. The resin used in the system is characterized to experimentally determine its working curve. This work enables us to compute the dimensions of a single layer cured using our system. The analytical model is validated by curing test layers on the system. The model computes layer dimensions within 5% error.Mechanical Engineerin

Development of a Capacitive Mems RF Power Sensor Without Dissipative Losses: Towards a New Philosophy of RF Power Sensing

The development of a novel radio frequency (RF) power sensor is presented based on capacitive micro electromechanical system (MEMS) technology, in which the signal is barely disturbed during the power measurement. Results of the first prototypes and improvements for the second generation of RF power sensors are given\ud \u

A micro-electro-mechanical-system-based thermal shear-stress sensor with self-frequency compensation

By applying the micro-electro-mechanical-system (MEMS) fabrication technology, we developed a micro-thermal sensor to measure surface shear stress. The heat transfer from a polysilicon heater depends on the normal velocity gradient and thus provides the surface shear stress. However, the sensitivity of the shear-stress measurements in air is less than desirable due to the low heat capacity of air. A unique feature of this micro-sensor is that the heating element, a film 1 µm thick, is separated from the substrate by a vacuum cavity 2 µm thick. The vacuum cavity prevents the conduction of heat to the substrate and therefore improves the sensitivity by an order of magnitude. Owing to the low thermal inertia of the miniature sensing element, this shear-stress micro-sensor can provide instantaneous measurements of small-scale turbulence. Furthermore, MEMS technology allows us make multiple sensors on a single chip so that we can perform distributed measurements. In this study, we use multiple polysilicon sensor elements to improve the dynamic performance of the sensor itself. It is demonstrated that the frequency-response range of a constant-current sensor can be extended from the order of 100 Hz to 100 kHz

Assessment of skill and technology indicators at the macro-micro levels in Sudan

In this paper we examine skill and technology indicators at the macro and micro levels in Sudan. Different from the Sudanese literature, a novel element in our analysis is that we use new primary data from the macro and firm surveys and we provide a new contribution and fill the gap in the Sudanese literature by examining five hypotheses on the causes and consequences of low skill and technology indicators at the macro and micro levels in Sudan. We verify our first hypothesis that the interaction between the deficient educational system -caused by low quality of education- and the high share of unskilled workers leads to poor provision of training; low skill levels; skills mismatch; low transfer of knowledge/external schooling effect; weak technology indicators and dependence on foreign technologies at the micro level. We confirm our second hypothesis that the poor local technology indicators/indigenous capability to build the local technology and heavy dependence on foreign technology can be attributed to lack of R&D activities/efforts, due to a lack of funding, low skill levels, weak linkages, lack of networks systems and collaboration between universities and industry/firms, low transfer of knowledge and a lack of entrepreneur perspective. We support our third hypothesis that the transfer of knowledge/external schooling effects is successful at the micro level but unsuccessful at the macro level due to low educational qualifications and deficient educational and training systems. We confirm our fourth hypothesis that skill and technology indicators are significantly determined by firm size and industry. We support our fifth hypothesis concerning the consistency of upskilling plans at the macro-micro levels. Finally, one advantage and interesting element in our analysis is that we provide a new contribution to the Sudanese literature, since we explain the causes, consequences and interaction between the low skill and technology indicators and the transfer of knowledge. We recommend further efforts to be made to improve skill and technology indicators and transfer of knowledge at the macro and micro levels which are all essential for economic growth and development in Sudan.Skill, technology, firm size, industry, Sudan

A community electrification project: combination of microgrids and household systems fed by wind, PV or micro-hydro energies according to micro-scale resource evaluation and social constraints

When electrifying isolated rural communities, usually standardized solutions have been implemented using the same technology at all the points. However these solutions are not always appropriate to the community and its population. This article aims to describe the technical design of the electrification system of the community of Alto Peru (in the region of Cajamarca, Peru), where the adequate technology was used at each area according to micro-scale resource evaluation and the socioeconomic requirements of the population. Specifically four technologies were implemented: wind microgrids in highlands, a micro-hydro power plant in the presence of a waterfall, a PV microgrid in a group of points sheltered from the wind and individual PV systems in scattered points with low wind potential. This project brought electricity to 58 households, a health center, a school, a church, two restaurants and two shops.Peer ReviewedPostprint (author’s final draft

Introducing a new technology to enhance community sustainability: An investigation of the possibilities of sun spots

The introduction of the Sun SPOT, Small Programmable Object Technology, developed by Sun Microsystems has been depicted as providing a revolutionary change in cyber physical interaction. Based on Sun Java Micro Edition (ME), this sensor technology has the potential to be used across a number of discipline areas to interface with systems, the environment and biological domains. This paper will outline the potential of Sun SPOTs to enhance community sustainability. An action based research project was carried out to investigate the potential uses of these technologies and develop a prototype system as a proof of concept. The research will compare Sun SPOTs with similar technologies, provide an assessment of the technology, and propose a number of possible implementations of the technology to enhance community sustainability