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Tanzania Journal of Engineering and Technology (TJET)

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Articles 151 - 180 of 211

Full-Text Articles in Industrial Engineering

A Comparison Of Three Numerical Methods Of Solutions Of Equations Describing Unsteady Gas Flow At Pipe Boundaries In Reciprocating Compressor Systems, M Mkumbwa Dec 1998

A Comparison Of Three Numerical Methods Of Solutions Of Equations Describing Unsteady Gas Flow At Pipe Boundaries In Reciprocating Compressor Systems, M Mkumbwa

Tanzania Journal of Engineering and Technology (TJET)

A number of finite difference schemes are available to study pressure fluctuation effects in unsteady pipe flows. This paper presents a comparison Of the predictions made by three such schemes of unsteadyjlow effects in a number of reciprocating compressor pipe-work systems. The finite difference schemes considered were;- a first order scheme known as the method Of characteristics, two second order schemes which were the Leapfrog method and MacCormacVs method. A reciprocating compressor simulation computer program was coupled with equations describing the cylinder thermodynamic processes with the pipe flow equations for steady non-homentropicflow. The comparison presented takes into account both the …

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New Technologies For Thermal Disposal Of Sewage Sludge, T Ogada Dec 1998

New Technologies For Thermal Disposal Of Sewage Sludge, T Ogada

Tanzania Journal of Engineering and Technology (TJET)

The traditional methods for the disposal of sewage sludge are landfilling, recycling as fertilisers in agricultural lands, dumping into sea and incineration. In thc recent past, Sludge incineration has been rapidly gaining ground duc to environmental constraints facing the Other methods. However, the cost of pollution control during sewage sludge incineration is currently very high due to the expensive flue gas treatment facility required. Futhermore, large quantity Of ash is produced which is highly contaminated with heavy metals and must be disposed off in special landfilling sites in order to avoid ground water pollution. To reduce the cost Of pollution …

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Experimental Study Of Domestic Charcoal Stoves, Simbo Kimario Dec 1998

Experimental Study Of Domestic Charcoal Stoves, Simbo Kimario

Tanzania Journal of Engineering and Technology (TJET)

The demand of fuelwood for domestic cooking especially the charcoal fuel is increasing in the urban settlements due to the increase in population of low income class earners who are the main consumers Of this type of fuel. This paper is presenting rhe results Of experiments conducted on the popularly used domestic charcoal stoves in Tanzania. The results revealed some significant differences on stoves performances. The type of insulation materials and some design features incorporated into the combustion chambers of the stoves had positive impacts in relative charcoal fuel saving. About two tons of charcoal fuel could be saved by …

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Technical And Economic Comparison Of Performance Between Farmer And Government Managed Irrigation Schemes In Tanzania: A Case Study Of Kapunga Irrigation Project, D Chemka Dec 1998

Technical And Economic Comparison Of Performance Between Farmer And Government Managed Irrigation Schemes In Tanzania: A Case Study Of Kapunga Irrigation Project, D Chemka

Tanzania Journal of Engineering and Technology (TJET)

This paper conwares the perforinance Of governnyent ro fanner-managed irrigation schemes at Kapunga Rice Project in Mbeya Region, south-west Tanzania. The results showed that the farmer-managed irrigation scheme (FMIS) performed better than the government-managed irrigation scheme (GMIS) in attaining good performance. Applicable indicators for farmer-managed irrigation scheme are as shown below with those of government-managed scheme indicated in brackets. Its overall irrigation efficiency was 61' percent (29 percent) average productivity was 3.2 ton/liG (2.2 ton/ha); economic profirability: internal rate of return was 3.2 percent (5 percent), benefit/cost ratio of 0.60 (0.14); while its financial profitability: internal rate of return was …

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The Significance And Effects Of Oil Injection On The Performance Of Sliding Vane Compressors., M Mkumbwa Dec 1998

The Significance And Effects Of Oil Injection On The Performance Of Sliding Vane Compressors., M Mkumbwa

Tanzania Journal of Engineering and Technology (TJET)

A computer model of a sliding vane air compressor was used to predict the behaviour of machines having different geometries operating at different conditions. The performance parameters which were calculated by the model were the free air delivery, power input and specific capacity which is defined as the free air delivery per unit of power input.The model also included the study of the effects of Oil injection on these mentioned compressor performance parameters. The paper describes the simulation model developed incorporating an analysis Of the effects of the oil injected into the compressor on lhe thermodynamic processes taking place in …

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A Study On Ring Pack Lubrication In Internal Combustion Engine, I Mshoro Dec 1998

A Study On Ring Pack Lubrication In Internal Combustion Engine, I Mshoro

Tanzania Journal of Engineering and Technology (TJET)

Most efthe lubricating oil from Internal Combustion Engine (ICE) is lost through piston rings. Hence, in order to optimally reduce ICE oil consumption, a better insight into tribology of the ring pack is required. This can only be achieved by an inwroved characterization of the lubricant behaviour within the opelating environment of the engine. In The present ieork, an optical tcchnique using laser- induced fluorescence was employed to measure oil film thickness within the ring pack. The experiment was conducted on a Phaser 1000 Series engine, whereby optical access to the ring pack was achieved by a fused silica-window positioned …

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Sustaina Bility Of Irrigation Schemes For Small-Scale Farmers: A Case Study Of Irrigation Scheme At Buleya Malima, Gwembe Valley, Zambia, Masinja R Jul 1998

Sustaina Bility Of Irrigation Schemes For Small-Scale Farmers: A Case Study Of Irrigation Scheme At Buleya Malima, Gwembe Valley, Zambia, Masinja R

Tanzania Journal of Engineering and Technology (TJET)

A study to determine facrors influencing sustainability of smallholder irrigation schemes was carried our a! Buleya Malima, Southern Province, 7_nnzbia. These factors included technical and socio-economic factors. found Out that the technical factors were 26.5, 64.5 and 9.2 percent for application efficiency, tailwater ratio and deep percolation, respectively, indicating that farmers wasted water mainly through tailwater runoff.From socio-economic point of view, the study indicated that the scheme lacked (i) farmer participation in designing and planning operation of the scheme (ii) managerial ability and innovativeness to form their own viable organisation: and (iii) formal training in technical operations of irrigation, infrastructure …

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Kiln Design And Fuel Wood Consumption In Fish Smoking, E Mushi Jun 1998

Kiln Design And Fuel Wood Consumption In Fish Smoking, E Mushi

Tanzania Journal of Engineering and Technology (TJET)

In this paper. a load flow solution for the Medium Voltage (MY) three-phase radial distribution in delta-delta (A — A) connected network supplying different line topologies such as three phase, phase to phase and single-wire earth return (SWER) networks is presented. The general voltage related network equations are developed using Kirchhoff's voltage and current laws. Development ofa solution to the loadflow analysis applying the developed general voltage related network equations is proposed in order to evaluate the network voltage profile. Various numbers of arrays are developed for the identification of the network under study. The proposed method is a new …

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Trends Of Microcomputer Technology In Developing Countries, With More Focus On Tanzanian Experiences: Achievements And Problems, Satoki Mahenge Jun 1998

Trends Of Microcomputer Technology In Developing Countries, With More Focus On Tanzanian Experiences: Achievements And Problems, Satoki Mahenge

Tanzania Journal of Engineering and Technology (TJET)

Trends of microcomputer technology in developing countries, including Tanzanian. is like a 'mixed bag' of achievement and problems. Although rhe technology has been available for many years in developed world, developing countries are responding to it differently due to differences in political and economic policies. Some countries have acrimonious policies on the technology, some not. There are countries which utilize fully the technology in work places and others are still at dilemma on the importation of the technology due to what is 'claimed to be a weak economy in the presence Of many other pressing needs'. Other countries seem to …

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Experimental Study Of Rural Brick Burning In Iringa And Mbeya Regions, E Mushi Jun 1998

Experimental Study Of Rural Brick Burning In Iringa And Mbeya Regions, E Mushi

Tanzania Journal of Engineering and Technology (TJET)

In this paper results are presented Of a study conducted between June and December 1997. on nine brick firing kilns in Iringa and Mbeya. The locations for rhe study were Mahenje and Iloniba in Mbeya Region and Igumbilo in Iringa region. Three kilns were investigated in each location. For each kiln the process was followed from the laying Of the bricks into a kiln to the opening Of thc kiln for renu)val Of the bricks in preparation for the selling. Different weights and tenperatures were Taken a,' different times. Firing wet bricks results in consumption of 33.63 % of the …

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Design Considerations For A Three-Phase Fluidized-Bed Bioreactor, S Manyele Jun 1998

Design Considerations For A Three-Phase Fluidized-Bed Bioreactor, S Manyele

Tanzania Journal of Engineering and Technology (TJET)

The design Of a three-phase fluidized bed bioreactor using novel biomass support for industrial wastewater treatment is reported in this paper. A column of 0.20 m diameter with variable height up to 6.60 m equipped with a foam breaker tank was designed, commissioned and operated. A novel biomass support, KMTR support, has been used Separate gas and liquid feeding systems were designed to facilitate proper bioreactor operation. A flat distriburor plate with 4 mm holes- diameter was desined A study on the hydrodynamic properties of the three-phase fluidized bed bioreactor revealed high values of bed expansion and air hold-ups. Purification …

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Design Approach For Small Scale Continuous, Steady State Plants, O Kaunde Dec 1994

Design Approach For Small Scale Continuous, Steady State Plants, O Kaunde

Tanzania Journal of Engineering and Technology (TJET)

One of the major steps in the design of a process plant is development of an appiopriate flowsheet. At this step, the technical solutions may be con- sidered in relation to the social and economic factors. In this paper, guide- lines for developing a flowsheet for continuous, steady State process in a developing country environment have been proposed. To illustrate the pro- posed guidelines, a case study involving design of an ethanol distillation plant has been used.

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Experimental Investigation On The Use Of Native Biomass As Biosorbents For Metal Pollutant Removal, R Litto Dec 1994

Experimental Investigation On The Use Of Native Biomass As Biosorbents For Metal Pollutant Removal, R Litto

Tanzania Journal of Engineering and Technology (TJET)

Waste water treatment is a perrnunent task. Many novel techniques have emerge in recent years and one of them is using biomass in removing heavy- metals. In this research screening and preliminary optimization experi- ments have identified different types of abundant biomass which can accu- mulate heavy metals such as Fe3*, C03•, Cu2+ and ftvm effluent. Cystoseira Myrica has a high uptake ofCr3+ while Sargassum Polycystum has been found to have a high uptake 0fFe3+. Observed biosorption kinet- ics shows rapid initial stage, followed by slower second stage and the amount of material adsorbed increases linearly as its concentration in …

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Improved Heat Transfer By Means Of Steam Injection In A Shell & Tube Heat Exchanger, O Kaunde Dec 1994

Improved Heat Transfer By Means Of Steam Injection In A Shell & Tube Heat Exchanger, O Kaunde

Tanzania Journal of Engineering and Technology (TJET)

When designing a heat exchanger; one aims at attaining high heat transfer rates SO as to minimise heat transfer area and therefore the overall cost. This paper presents a method of improving the overall heat travsfer coef- ficient of a conventional shell and tube heal exchanger. The method in- volves injecting steam into the process fluid as it enters the heat exchanger thus effecting mixing of fluid as it travels along the exchanger Tests car- • ried out using this technique showed a significant increase in the overall heat transfer coefficient values.

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

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

Tanzania Journal of Engineering and Technology (TJET)

Methods of measuring electrical sensitivity of a dust layer have been outlined and the porous electrodes cell was used to measure the electrical resistivity of a dust layer and to determine the influence of various parameters. Dust layer thickness and applied voltage had no influence. Resistivity depended 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 results may help in understanding the performance of electrically enhanced fabric filters, which are influenced …

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Evaluation Of The Influence Of The Magnetic System In Relays, D Chambega Dec 1994

Evaluation Of The Influence Of The Magnetic System In Relays, D Chambega

Tanzania Journal of Engineering and Technology (TJET)

The paper evaluates the influence of different cores on the performance of relays. In particular two types ofc-cores, all made from IOW quality mag- netic steel, are considered. The two cores, one butt-constructed and the other interleaved, are mathematically modelled and the tesults are analyzed and obtained experimentally. Then the two sets of results are compared with those ofa c-shaped core of excellent magnetic material with the aim of qualifying the influence of the core material. It is observed that the method of constructing the core also influences the performance.

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Power Shedding Experiences And Lessons In A Township, Alexander Kyaruzi Dec 1994

Power Shedding Experiences And Lessons In A Township, Alexander Kyaruzi

Tanzania Journal of Engineering and Technology (TJET)

This paper presents how power shedding by taking out one of the trans- former high voltage fuses causes phase imbalance. And for the same elec- nicc,l energy output generator fuel consuntption with unbalanced phases is 12.5% of The fuel consunwtion with balanced phases. Furthermore it is shown thal energy efficient lighting by use of energy efficient bulbs can reduce load shedding.

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Polymer Supported Z-N Catalysts For C2h4-Polymerization,I: Development Catalyst Preparation Method, S Mteza Dec 1994

Polymer Supported Z-N Catalysts For C2h4-Polymerization,I: Development Catalyst Preparation Method, S Mteza

Tanzania Journal of Engineering and Technology (TJET)

Substantial improvement of low sensitivity pressure transducers aiming at obtaining a more realistic output signal is discussed. The output signal direct from these transducers has deficiencies of amplitude attenuation and phase lag, thus the measured values are not necessarily the true in- stantaneous values. In order to correct for such shortcomings the unit step response of these transducers is also studied experimentally. A math- ematical model is established based on the experimental results to build up a compensation circuit which is then included in the instrumentation setup to eliminate these deficiencies. The effectiveness of the compensated transducer is demonstrated by …

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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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Electricity Consumption Patterns In Domestic House Holds, H Kadete Jun 1994

Electricity Consumption Patterns In Domestic House Holds, H Kadete

Tanzania Journal of Engineering and Technology (TJET)

Electricity tariff increases from 1988 to 1992 are presented. They are Compared with salaries paid to parastatal workers over the same period. Monthly expenditures on electricity are also presented. Electricity con- sumption profiles have been recorded. The typical end use electrical ap- pliances for each household category have been identified. About 69% of electricity is used for cooking in high demand households. In medium demand households electricity used for lighting dominates ar about 49%. Measurements indicate a 3 peak power consumption profile for domestic dwellings. Voltages of 180V were recorded instead of the expected 230V nominal. Power factor is nor …

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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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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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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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Improvement Of Solar Salt Works Performance, J Katima Dec 1993

Improvement Of Solar Salt Works Performance, J Katima

Tanzania Journal of Engineering and Technology (TJET)

Coal, asphalt, black oil paint, naphthol green b and alkali blue 6b were testedfor improvement Of solar energy utilisation in solar salt manufacture. It was found that the use of alkali blue 6b dye dissolved in raw seawater improves efficiency by 3.6 percent. Both modifications could increase solar salt works with a coal coated surface than one employing raw seawater dyed with alkali blue 6b.

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A Check Parameter Method For Use In Designing Relays, H Kadete Dec 1993

A Check Parameter Method For Use In Designing Relays, H Kadete

Tanzania Journal of Engineering and Technology (TJET)

Low quality magnetic steel available locally has been successfully used as core material for a relay. New design principles as well as construction procedure used in development of a prototype are presented. Then the new approach is assessed and found to deliver acceptable accuracy.

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Critical Evaluation Of The Effects Of Changes Made To Roughing Filters Of Mpira-Balaka Plant On Its Treatment And Operational Performance, C Zulu Dec 1993

Critical Evaluation Of The Effects Of Changes Made To Roughing Filters Of Mpira-Balaka Plant On Its Treatment And Operational Performance, C Zulu

Tanzania Journal of Engineering and Technology (TJET)

Mpira Balaka, a full scale rural water supply project was constructed in Ntcheu, Malawi, in 1988 utilising Slow Sand Filtration (SSF) as the main treatment process and roughing filtration as the pretreatment method,following the promo- tion of this technology by various international institutions. During the rainy seasons, the treatment plant for Mpira Balaka failed to cope with the high raw water turbidity, resulting into very short filter run times and hence also to unavoidable distribution Of very turbid water to the rural communi- ties as a result Of by-passing the filters. Of the fifty or so existing rural projects in …

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Optimum Design For Spring With Orthogonal Design Method, Han Fu - Jie Jun 1993

Optimum Design For Spring With Orthogonal Design Method, Han Fu - Jie

Tanzania Journal of Engineering and Technology (TJET)

Orthogonal design method is a sort of direct optimum method, by which the op- timal result may be obtained through simple computation and analysis. This method has gained increasingly extensive interest in scientific research, engineering design, end production management as well. The orthogonal table is the basic instrument for carrying out optimum design with orthogonal design method. It is a mathernatical table established On the basis Of the idea of isostatic distribution. As various levels may appear in any column, it makes a partial experiment contain levels of all factors furthermore. RII combina- tions of any two columns may appear …

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