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Articles 26251 - 26280 of 27330

Full-Text Articles in Engineering

Hazards Inherent In The Use Of Electricity, Alexanda Kyaruzi Jun 1994

Hazards Inherent In The Use Of Electricity, Alexanda Kyaruzi

Tanzania Journal of Engineering and Technology (TJET)

This paper describes hazards associated with thc use of electricity, empha- sis is given to hazards due to electric shocks. A survey carried Out by the author indicated that 68.5 % of all reported accidents and 55.3 % of all fatal accidents are due to people Coming into contact with normally non current carrying metallic parts. The necessary conditions which need to bc present in an electric system for electric shock to occur are described. How the human body responds to Various severity of electric shock is dis- cussed. Possible solutions, and how to prevent or minimise the effect Of …

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Quality Problems Facing Tanzanian Industrial Firms, M Msafiri Jun 1994

Quality Problems Facing Tanzanian Industrial Firms, M Msafiri

Tanzania Journal of Engineering and Technology (TJET)

This paper reports on the results of a study of quality problems facing Tanzanian industrial firms. The results show that Tanzanian firms do not set goals with respect to quality and quality management, thus their qual- ity performance is generally poor. A Ithough there are a number of opera- tional problems constraining the companies, the main problems lie with the internal management of the quality function. Extensive ideas and sug- gestions for improving the performance of the quality function are given.

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Regionalization Of Hydrologic Information In Tanzania (Low Flows), Onyekwuluje C Jun 1994

Regionalization Of Hydrologic Information In Tanzania (Low Flows), Onyekwuluje C

Tanzania Journal of Engineering and Technology (TJET)

Hydrologic infornjation is required for the planning and design Ofwater resource projects. However, Hydrologic infonnation is always lacking at points of interest. Regionalization is ained at estimating hydrologic infor- mation such as low flow statistics at ungauged sites. Hydrologic informa- tion from 63 catchments in Tanzania has been analysed. In this paper, pooled flow duration curves for 1, IO, 30, 60, and 90 days duration have been established. Regression equations between the low flow indices (i.e. 95 percentile and for a IO day duration, average annual yield (AAY), av- erage daily flow (ADE)) and catchment characteristics were developed. The pooled …

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Pulping Of Sisal Fibres: Effects Of Chemical Concentration, Na-Zs03/Na2c03 Ratio And Fibre To Chemical Ratio, J Katima Jun 1994

Pulping Of Sisal Fibres: Effects Of Chemical Concentration, Na-Zs03/Na2c03 Ratio And Fibre To Chemical Ratio, J Katima

Tanzania Journal of Engineering and Technology (TJET)

This paper reports on pulping of hard fibres extracted from the leaves Of agave sisalana using sodium sulphite buffered with sodium carbonate as pulping chemical. The cooking was carried Out at 1680Cfor a cooking period of 6 hours, with varying chemical concentration, sodium sulphite to sodium carbonate ratio and fibre to chemical ratio. The results show thar boll! the pulp yield and pulp viscosity decæase with increasing chemi- cal concentration, whereas Kappa number of pulp decreases to a limit of about 16.45. Brightness increases significantly with an increase in the ra- rio of Na2S03/Na2C03. The pulp yield obtained indicated the …

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Measurement Of Dust Resistivity And The Effect Of Filter Operating Parameters On Its Value, Allan Issangya Jun 1994

Measurement Of Dust Resistivity And The Effect Of Filter Operating Parameters On Its Value, Allan Issangya

Tanzania Journal of Engineering and Technology (TJET)

Methods sed to measure the electrical resistivity of a dust layer and to determine the influence of various parameters. Dust layer thickness and applied voltage were found to have no influence. Resistivity depends on particle size, packing density, temperature, and air relative humidity. Glass beads and limestone powders of different mean particle sizes were used. Temperature was varied from 20–100 °C and air moisture ranged from dry to near saturation. The findings may help in understanding electrically enhanced fabric filters, whose performance is influenced by the resistivity of the collected dust layer.

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Optimal Capacity Allocation Truck Industry In Tanzania:A Case Of National Transport Corporations(Ntc), R Mgaya Jun 1994

Optimal Capacity Allocation Truck Industry In Tanzania:A Case Of National Transport Corporations(Ntc), R Mgaya

Tanzania Journal of Engineering and Technology (TJET)

This paper tries to examine truck transportation service in Tanzania, particularly, in National Transport Corporation’s subsidiary companies - Regional Transport Companies. It provides an analysis based on operations research approach on resource allocation, specifically, truck allocation, with an aim of trying to minimize running costs and hence improve profits. It is established that there had been higher running costs and hence decline of profits in some Regional Transport Companies due to misallocation of capacity. However, this problem had been compounded by some other factors as discussed in the paper. It is recommended that these Regional Transport Companies and other transport …

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Dual Versus Single Spark Plug: A Critique, I Mshoro Jun 1994

Dual Versus Single Spark Plug: A Critique, I Mshoro

Tanzania Journal of Engineering and Technology (TJET)

Dual spark plugs are occasionally employed on certain modern Spark lg- nited (S') engines, viz lean burn engines. Their benefit has generally been noticed in the operating conditions whenfuel-air mixture is very lean, or when a larger proportion of EGR has been employed, or during the part load conditions and so on. An extensive literature survey has indi- cared an interesting spectrum of reasons for gains due to the dual spark plug. A consistent explanation is found to be missing which can describe the behaviour of the engines with single versus dual spark plugs There are quite "few researchers who …

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Influence Of Turbulence On Methane-Air Flame Speed, E Mushi Jun 1994

Influence Of Turbulence On Methane-Air Flame Speed, E Mushi

Tanzania Journal of Engineering and Technology (TJET)

Experimental study Of the influence qfturbulence on flame speed for meth- ane-air mixtures has been conducted in afan stirred bomb using schlieren photography. It has been observed that turbulence increases flame speed but above KLe=O. 18 (KLe is the product Of the dimensionless Karlovitz flame stretch factor and the Lewis number) turbulence quenches the flame. Inminarflame kernel is observed to prevail in the early stages of flame development in a turbulent mixture. Further, the laminar burning velocity plays a significant role in turbulent combustion. It is proposed that the increase in flame speed is a result of flame wrinkling.

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An Alternative Method Of Interfacing A Dc Motor To A Microprocessor For Mo- Tion Control, M Selekwa Jun 1994

An Alternative Method Of Interfacing A Dc Motor To A Microprocessor For Mo- Tion Control, M Selekwa

Tanzania Journal of Engineering and Technology (TJET)

A Simple and cheap alternative method Of interfacing a permanent mag- net dc motor to a motion control using switch- ing transistor motor drivers is presented. This method involves the use Of very few transistor-transistor logic (TTL) devices and a 555 timer to pro- duce a pulse width modulated (P WM) signal which is required by the mo- ror driver. The motor driver in this case should be of an H-bridge type. Like other methods currently in use, it relieves the MPU of all timing func- tions which are necessary in the generation of P WM signals. The present method, …

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Suitability Of The Present Strategic Information Technology Planning (Sitp) Methodologies To The Developing Countries, A Victor Jun 1994

Suitability Of The Present Strategic Information Technology Planning (Sitp) Methodologies To The Developing Countries, A Victor

Tanzania Journal of Engineering and Technology (TJET)

The needfor strategy formulation, or in general terms strategic planning, for IT is considered as one of the most important aspects of IT manage- ment. To this end, there are a number of IT strategy formulation method- ologies world-wide. These methodologies were developed over a span of time, starting from mid 1960's when IT use started to become a serious issue in the developed countries, and continued with the trends in IT de- velopment and use, as was applicable in those countries. Morc recent of the methodologies were developed through improvements on earlier ones, and based on the new challenges …

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Impression Creep Behavior In Weldments, S.H. Wang Jun 1994

Impression Creep Behavior In Weldments, S.H. Wang

Journal of Marine Science and Technology–Taiwan

At high temperature application, the failures of dissimilar metal weldments associated with the relevant degradation processes, which include chemical diffusion, oxide notching, precipitation, softening of the heat affected zone (HAZ), and creep type voids leading to cracking. This reveals that a creep in a gradient related to the microstructural degradation exists. The impression creep test was applied to monitor the effects of microstructural gradients on the localized high temperature creep properties in an autogeneous GTA aluminum weldment, and an austenitic stainless steel to ferritic steel dissimilar metal weldment respectively. To simplify the complexity of microstructural gradients, multipass weldments in A36 …

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A Study Of Chloride Diffusion Properties Of Concrete At Early Age, W.D. Yeih, R. Huang, J.J. Chang Jun 1994

A Study Of Chloride Diffusion Properties Of Concrete At Early Age, W.D. Yeih, R. Huang, J.J. Chang

Journal of Marine Science and Technology–Taiwan

Existence of chloride ions in concrete may accelerate reinforcement corrosion. Chloride ions can penetrate into the concrete by the diffusion process even if no major cracks exist. It is well known that properties of concrete will change with time since the hydration reaction continues for a long time, which implies that the diffusion coefficient of concrete is a time-dependent function. In this research, the diffusion behavior is focused on early-age mortar and concrete. It is shown that the diffusion coefficient changes dramatically at early age; and the control of interface property is significantly important to chloride diffusion. The effect by …

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The Use Of Ac And Dc Methods For Corrosion Monitoring Of Reinforced Concrete Members In Marine Environment, R. Huang, W.D. Yeih, J.J. Chang, C.C. Yang Jun 1994

The Use Of Ac And Dc Methods For Corrosion Monitoring Of Reinforced Concrete Members In Marine Environment, R. Huang, W.D. Yeih, J.J. Chang, C.C. Yang

Journal of Marine Science and Technology–Taiwan

Reinforced concrete is the most common engineering material for civil structures. The durability of the concrete structures depends mainly on the corrosion of steel reinforcement. In general, concrete produces an alkaline environment for steel which passivates it, so preventing corrosion. Provided this passivity is maintained, no problem should arise with steel reinforcement. However, in certain environment, chloride ions can locally destroy very protective passive film of reinforcement even though concrete is still alkaline. This paper presents the corrosion results of reinforcing steel in concrete members in marine environment using the AC impedance technique and DC method.

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Vibration Analysis Of Timoshenko Beams Traversed By Moving Loads, Yih-Hwang Lin Jun 1994

Vibration Analysis Of Timoshenko Beams Traversed By Moving Loads, Yih-Hwang Lin

Journal of Marine Science and Technology–Taiwan

The purpose of this research is to apply the finite element method for dynamic analysis of Timoshenko beams traversed by moving loads. When an elastic structure is subjected to moving loads, the induced displacements and stresses are much higher than those of static loading conditions. Due to the prevalence of high speed machinery and the use of light and flexible structures to reduce the material cost, structural weight, and space requirement, dynamic analysis of such systems becomes crucial to ensure structural safety and required accuracy. In this study, the shear effect and rotary inertia were included for the analysis of …

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Analysis Of Homogeneous Slurry Pipe Flow, R. C. Chen Jun 1994

Analysis Of Homogeneous Slurry Pipe Flow, R. C. Chen

Journal of Marine Science and Technology–Taiwan

An analysis is performed for the solid-liquid slurry pipe flow in the homogeneous flow regime. The transport and concentration equations are constructed based on two-liquid postulation and modified Rouse-Schmidt diffusion relation. By considering the interphase interaction effects, a general k-e model is applied to describe the turbulent kinetic energy production and dissipation. Coupling with the physically-defined parameters, this model is able to obtain the axial velocities of the solid and liquid phases, the solid concentration distribution and the liquid turbulent kinetic energy and dissipation rate. Excellent agreement between the calculated axial velocity profiles and the experimental data obtained by Chen …

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Viscoelastic Buckling And Postbuckling Of Circular Cylindrical Laminated Shells In Hygrothermal Environment, N.N. Huang Jun 1994

Viscoelastic Buckling And Postbuckling Of Circular Cylindrical Laminated Shells In Hygrothermal Environment, N.N. Huang

Journal of Marine Science and Technology–Taiwan

The viscoelastic buckling and postbuckling behaviors of fiber-reinforced plastic (FRP) circular cylindrical shells, operating in the hygrothermal environment, subjected to uniform external pressure are investigated in this study. The FRP is assumed to be a hy grothermorheologically simple material (HTSM). The analysis is conducted within the framework of the quasielastic approach. The finite element method is employed to examine both buckling and postbuckling behaviors for shells having arbitrary layups. The arc-length algorithm is incorporated into the finite element formulations to trace the postlimit equilibrium path. The structural responses of Glass/Epoxy shells are reported.

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Analysis Of Three-Dimensional Pile Groups, M.T. Liang, Y. Liu Jun 1994

Analysis Of Three-Dimensional Pile Groups, M.T. Liang, Y. Liu

Journal of Marine Science and Technology–Taiwan

A numerical technique is presented in the analysis for loading behavior of general three-dimensional pile groups. The striking characteristics of the pile-group model may include raked pile, different pile sizes, non-uniform pile sections, soil inhomogeneit y, soil nonlinearity, and pile-soil-pile interaction. A typical six-pile group is analyzed and the results are compared with that obtained by four other computer programs that are based on different approaches. The computed solutions are shown to have reasonally good agreement with the measured values.

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Bs News Jun 1994

Bs News

Building Services Engineering

No abstract provided.

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Bs News May 1994

Bs News

Building Services Engineering

No abstract provided.

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Ole Miss Engineer 1994 Apr 1994

Ole Miss Engineer 1994

Ole Miss Engineer

No abstract provided.

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Bs News Apr 1994

Bs News

Building Services Engineering

No abstract provided.

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Technology Transfer: A View From The Trenches, Harvey Drucker Mar 1994

Technology Transfer: A View From The Trenches, Harvey Drucker

RISK: Health, Safety & Environment (1990-2002)

Dr. Drucker, who has lab-wide responsibility for technology transfer at Argonne National Laboratory, argues that transferring rights in discoveries made through tax supported research to private entities can contribute to public welfare in many ways.

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Overview Of Federal Technology Transfer, Lawrence Rudolph Mar 1994

Overview Of Federal Technology Transfer, Lawrence Rudolph

RISK: Health, Safety & Environment (1990-2002)

Mr. Rudolph reviews approximately thirteen years of legal and political developments that have contributed to laws governing the extent to which private firms may secure rights in technology at least partly developed with federal funds.

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Bs News Mar 1994

Bs News

Building Services Engineering

No abstract provided.

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Coping With The Risk Of Cancer In Children Living Near Power Lines, Eileen N. Abt Jan 1994

Coping With The Risk Of Cancer In Children Living Near Power Lines, Eileen N. Abt

RISK: Health, Safety & Environment (1990-2002)

Ms. Abt briefly summarizes evidence linking power lines with a possible increase in risk of childhood cancer. She also recounts how, although many experts remain skeptical of causality, public fears, whether or not warranted, have themselves created serious problems. Finally, she proposes ways to address those problems.

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Acceptable Risk: A Conceptual Proposal, Baruch Fischhoff Jan 1994

Acceptable Risk: A Conceptual Proposal, Baruch Fischhoff

RISK: Health, Safety & Environment (1990-2002)

Challenging the "de minimis risk" concept, Dr. Fischhoff argues that risks ought not to be considered apart from a particular technology's benefits. He argues, too, that the acceptability of particular kinds of risks should not be determined without considering the views of all persons who may be exposed. Finally, building upon the "reasonable person" construct, he suggests ways those goals might be achieved.

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Concrete Beam Design Optimization With Genetic Algorithms, Siripong Malasri, D. A. Halijan, M. L. Keough Jan 1994

Concrete Beam Design Optimization With Genetic Algorithms, Siripong Malasri, D. A. Halijan, M. L. Keough

Journal of the Arkansas Academy of Science

This paper demonstrates an application of the natural selection process to the design of structural members. Reinforced concrete beam design is used as the example to show how various chromosomes representing a design solution can be formulated. Fitter chromosomes (or better solutions) have a better chance of being selected for cross over; this in turn creates better generations. Random mutation is used to enhance the diversity of the population. The evolution progresses through several generations, and the best solution is then used in the design. The method gives reasonable results, but sometimes a local (as opposed to the global) optimized …

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Application Of Machine Learning Principles To Modeling Of Nonlinear Dynamic Systems, Murray R. Clark Jan 1994

Application Of Machine Learning Principles To Modeling Of Nonlinear Dynamic Systems, Murray R. Clark

Journal of the Arkansas Academy of Science

A method for the development of mathematical models for dynamic systems with arbitrary nonlinearities from measured data is described. The method involves the use of neural networks as embedded processors in dynamic system simulation models. The technique is demonstrated through generation of models for anharmonic oscillators described by the Duffing Equation and the Van der Pol Equation from measured input/output data. It is shown that high quality models of these systems can be developed using this technique which are efficient in terms of model size. Using neural networks as embedded processors, accurate models of the Duffing Oscillator and the Van …

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Bs News Jan 1994

Bs News

Building Services Engineering

No abstract provided.

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Method For Determining Atmospheric Aerosol Optical Depth Using Solar Transmission Measurements, Felix Tendeku Jan 1994

Method For Determining Atmospheric Aerosol Optical Depth Using Solar Transmission Measurements, Felix Tendeku

Journal of the Arkansas Academy of Science

A multiple wavelength radiometer instrumentation has been developed and used to measure solar irradiance in a water vapor absorption band in the near-infrared region. From these measurements the total atmospheric optical depth at each wavelength of observation is deduced using a linear least-squares fitting method. An iteration technique, based on a power law wavelength dependence of aerosol optical depth, is employed to retrieve aerosol optical depth from the total optical depth data. The technique permits simultaneous determination of precipitable water vapor amount.

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