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Articles 2761 - 2790 of 3572

Full-Text Articles in Operations Research, Systems Engineering and Industrial Engineering

The Effect Of Rotation And Temperature On The Inhibition Performance Of Cashew (Anacardium Occidentale L.) Nut Shell Liquid On Co2 Corrosion Of Carbon Steel, J Mutasingwa Dec 2008

The Effect Of Rotation And Temperature On The Inhibition Performance Of Cashew (Anacardium Occidentale L.) Nut Shell Liquid On Co2 Corrosion Of Carbon Steel, J Mutasingwa

Tanzania Journal of Engineering and Technology (TJET)

A natural extract of cashew nut shells, Cashew Nut Shell Liquid (CNSL) was investigated as a corrosion inhibitor for carbon steel in 3% NaCl solutions saturated with CO2 gas using electrochemical techniques (i.e. potentiodynamic polarization and ac-impedance). The investigation was performed at different temperatures under static and dynamic conditions using a Rotating Disk Electrode (RDE). It was found that CNSL reduces the electrochemical processes taking place on carbon steel undergoing corrosion. The percentage inhibitor efficiency increases with increase in CNSL concentration and decreases with rise in temperature. Better performance at low CNSL concentration was registered under dynamic conditions and room …

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Potential Use Of Waterguard As A Disinfectant For Domestic Water Use, Yohana L Dec 2008

Potential Use Of Waterguard As A Disinfectant For Domestic Water Use, Yohana L

Tanzania Journal of Engineering and Technology (TJET)

been identified as an alternative method for treatment of domestic drinking water. The aim of this study was to investigate the effectiveness of Water Guard in disinfecting drinking water from different sources drawn from Kinondoni district, Dar es Salaam as well as to establish appropriate dosage that can be used during the treatment. Results showed that, a dose of 4.0mL per 20 litrer of water guard is sufficient for disinfection of urban water sources. The above prescribed doses provide 100% disinfection efficiency with residue chlorine of less than 0.3mg/l. Water with turbidity values of 30-35 NTU, chlorine dosage of 8mL/20 …

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Investigation Of The Effect Of Particle Size On Groundnut-Oil Solvent Extraction, S Manyele Dec 2008

Investigation Of The Effect Of Particle Size On Groundnut-Oil Solvent Extraction, S Manyele

Tanzania Journal of Engineering and Technology (TJET)

An investigation of the effect of particle size on the performance of vegetable oil recovery by solvent extraction is reported. Experiments were conducted using soxhlet extractor, groundnuts and n-hexane. Samples were grouped into mean particle sizes of 0.25, 0.75, 1.3, 3.3, and 7.5 mm using standard sieves. The effect of particle size was studied for extraction time intervals of 1, 2, 3, 4, 5 and 8 hours. The oil yield, oil recovered per kg solvent used, kg solvent lost per unit time, and the rate of extraction (kg oil recovered per hour) decreased with increasing particle size. Meanwhile, the percent …

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The Systemic Nature Of Action Learning Programmes, G Mwaluko Dec 2008

The Systemic Nature Of Action Learning Programmes, G Mwaluko

Tanzania Journal of Engineering and Technology (TJET)

A lot of attention has been paid on action learning in the last four decades or so and the success of such programmes has also been widely publicized. But why have these programmes been so effective in helping organizations cope with change? Many authors state that the success of such programmes is due to the fact that they link learning to actions. Yet others claim that action learning programmes succeed because they involve employee empowerment and provide a much greater learning curve. In this paper the authors hold that action learning programmes succeed because they are partly systemic and can …

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Analytical Modeling Of A Large Local Area Network - Part I: Internet Traffic Characterization, Mathew Luhanga Dec 2008

Analytical Modeling Of A Large Local Area Network - Part I: Internet Traffic Characterization, Mathew Luhanga

Tanzania Journal of Engineering and Technology (TJET)

The goal of both IP network operators and the end users is to get the highest performance from the system for a given cost. This makes Performance a key criterion in the design, procurement, and use of computer and communication systems. In order to address problems associated with performance degradation of operational communications systems, over the last decade, traffic engineering techniques have emerged in an attempt to optimize communication systems’ performance and ensure more efficient use of their resources. One of these techniques is analytical modeling. Analytic performance models are an excellent tool for quickly evaluating the performance of operational …

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Identification Of Unbalanced Forces And Foundation Parameters Of Rotating Machines From Vibration Measurements, Nalitolela G Dec 2008

Identification Of Unbalanced Forces And Foundation Parameters Of Rotating Machines From Vibration Measurements, Nalitolela G

Tanzania Journal of Engineering and Technology (TJET)

A technique is described to use measured vibration data of a rotating machine and its foundation to identify unbalanced forces, stiffness and damping parameters of the mountings, and the parameters of the foundation. It is based on an idealisation treating the rotor, the machine structure and the foundation as rigid masses supported by springs and dampers. Operational vibration data of the machine and its foundation before and after the rotating unbalanced forces are perturbed by adding unbalanced mass to the rotor are used in the identification procedure. Once the parameters are identified, dynamic forces transmitted to the foundation can be …

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Design And Development Of A Prototype For A Web-Based Interface For Online Material For Tanzanian Youth, Mjema A.M Dec 2008

Design And Development Of A Prototype For A Web-Based Interface For Online Material For Tanzanian Youth, Mjema A.M

Tanzania Journal of Engineering and Technology (TJET)

A prototype of a web-based interface for an online database was developed to be used by youth organizations in Dar-es-Salaam. A participatory approach involving secondary students in the identification of user interface requirements, in designing and testing the prototype was used. A questionnaire was designed and manned in seven secondary schools in Dar-es-Salaam to estimate the Internet usage. Interviews were conducted to countercheck the questionnaire responses. The interview and the questionnaire helped to come up with a set of user requirements for the web-based interface of an online information search. From the specifications of the user requirements the author was …

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Optimal And Heuristic Resource Allocation Policies In Serial Production Systems, Ramesh Arumugam Dec 2008

Optimal And Heuristic Resource Allocation Policies In Serial Production Systems, Ramesh Arumugam

All Theses

We have studied the optimal server allocation policies for a tandem queueing system under different system settings. Motivated by an industry project, we have studied a two stage tandem queueing system with arrival to the system and having two flexible servers capable of working at either of the stations. In our research, we studied the system under two different circumstances: modeling the system to maximize throughput without cost considerations, modeling the system to include switching and holding costs along with revenue for finished goods. In the maximizing throughput scenario, we considered two different types of server allocations: collaborative and non-collaborative. …

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Effective Vr: Interplay Of Presence, Perception, Fidelity And Transfer Effects In The Development Of Inspection Training Simulators, Sajay Sadasivan Dec 2008

Effective Vr: Interplay Of Presence, Perception, Fidelity And Transfer Effects In The Development Of Inspection Training Simulators, Sajay Sadasivan

All Dissertations

Increased emphasis on aircraft inspection to ensure aviation safety has resulted in the need for a better trained workforce of aircraft maintenance personnel. Aircraft inspection is mostly visual in nature. Thus it has led to the development of computer simulators to train human inspectors performing the inspection task. However, the lack of immersion and interaction in such simulators has led to limited effectiveness and adoption. Using advances in graphics and virtual reality technology, there is an increase the sense of involvement in using these simulators. Though technology is available to provide higher levels of immersion, it is expensive. It is …

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A Computer-Based Economic Analysis For Manufacturing Process Selection, Manocher Djassemi Nov 2008

A Computer-Based Economic Analysis For Manufacturing Process Selection, Manocher Djassemi

Industrial Technology and Packaging

An important part of financial planning in product development is considering whether the capital expenditures meet volume and cost goals. A good business plan should provide investors with the implications of process selection on the company's bottom line. It is estimated that there are least 1000 manufacturing processes and sub-processes. Considering the number of process choices and quantity of cost data, an economic analysis for process selection may pose a challenge for decision makers. This paper provides an insight to Ashby’s cost modeling method for generating an estimate of unit product cost. The cost model provides a broad indicator for …

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Drop Impact Dynamic Response Study Of Jedec Jesd22-B111 Test Board, Michael Krist, Jianbiao Pan, Andrew Farris, Nicolas Vickers Nov 2008

Drop Impact Dynamic Response Study Of Jedec Jesd22-B111 Test Board, Michael Krist, Jianbiao Pan, Andrew Farris, Nicolas Vickers

Industrial and Manufacturing Engineering

Mobile and handheld electronic devices are prone to being dropped. This drop event may result in failure of solder joints inside these devices. The need for RoHS compliant boards coupled with the demand for reliable electronics has resulted in the development of the JEDEC Standard JESD22-B111 to standardize the method of drop testing surface mount electronic components. However, there has been little study on the effects of additional mass on the board and rigidity of the board on drop test reliability. This paper examines the drop impact dynamic responses of the JEDEC JESD22-B111 board. Of interest are the effects of …

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The Effect Of Ultrasonic Frequency On Gold Wire Bondability And Reliability, Jianbiao Pan, Minh-Nhat Le, Cuong Van Pham Nov 2008

The Effect Of Ultrasonic Frequency On Gold Wire Bondability And Reliability, Jianbiao Pan, Minh-Nhat Le, Cuong Van Pham

Industrial and Manufacturing Engineering

This paper presents a systematic study on the effect of 120KHz ultrasonic frequency on the bondability and reliability of fine pitch gold wire bonding. The study was carried out on a thermosonic ball bonder that is allowed to easily switch between ultrasonic frequency of 60KHz and 120 KHz by changing the ultrasonic transducer and the ultrasonic generator. Bonding parameters were optimized through design of experiment methodology for four different cases: 25.4 μm wire at 60 kHz, 25.4 μm wire at 120 kHz, 17.8 μm wire at 60 kHz, and 17.8 μm wire at 120 kHz. The integrity of wire bonds …

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Board Level Failure Analysis Of Chip Scale Package Drop Test Assemblies, Nicholas Vickers, Kyle Rauen, Andrew Farris, Jianbiao Pan Nov 2008

Board Level Failure Analysis Of Chip Scale Package Drop Test Assemblies, Nicholas Vickers, Kyle Rauen, Andrew Farris, Jianbiao Pan

Industrial and Manufacturing Engineering

This paper presents the failure analysis results of board level drop tests. In this study, the test vehicle was designed according to the requirements of the Joint Electron Device Engineering Council (JEDEC) drop test board. The test vehicle was assembled with 15 chip scale packages (CSPs) each having 228 daisy-chained 0.5 mm pitch solder joints using Sn-3.0 wt% Ag-0.5 wt% Cu (SAC305) lead free solder. Assemblies were drop tested using three different peak accelerations of 900 G, 1500 G, 2900 G, with 0.7 ms, 0.5 ms, and 0.3 ms pulse durations, respectively. Scanning electron microscopy (SEM) with energy dispersive spectroscopy …

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Work In Progress - Enhancing Student-Learning Through State-Of-The-Art Systems Level Design And Implementation, Albert A. Liddicoat, Jianbiao Pan, James G. Harris, Dominic J. Dal Bello, Lynne A. Slivovsky Oct 2008

Work In Progress - Enhancing Student-Learning Through State-Of-The-Art Systems Level Design And Implementation, Albert A. Liddicoat, Jianbiao Pan, James G. Harris, Dominic J. Dal Bello, Lynne A. Slivovsky

Industrial and Manufacturing Engineering

The curriculum for undergraduate engineering programs is often partitioned into several courses that are taught in isolation followed by a single culminating senior design or capstone project experience. In the senior design class students being to synthesize the knowledge and skills that they acquired through the engineering curriculum. This paper presents lower and upper division course and curricular changes made to accommodate learning objectives that better prepare students for project-based learning. These learning experiences and skills include: systems level design, experience with state-of-the-art Computer Aided Design (CAD) tools, printed circuit board (PBC) design, design for manufacturability, electronics assembly, project management, …

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Alternative Binder Carbide Tools For Machining Superalloys, Daniel J. Waldorf, Michael Stender, Scott Liu, Daniel Norgan Oct 2008

Alternative Binder Carbide Tools For Machining Superalloys, Daniel J. Waldorf, Michael Stender, Scott Liu, Daniel Norgan

Industrial and Manufacturing Engineering

This study examines the performance of a new class of wear-resistant but economical cutting tools produced by varying the binder composition of standard cemented carbide composites. By replacing some or all of the cobalt binder with rhenium and nickel-based superalloy, a stronger composite tool results, potentially capable of machining heat-resistant superalloys at significantly higher cutting speeds. Sample tools with alternative binder were produced and compared to standard tools bound with cobalt only. Turning experiments on Inconel 718 were run to evaluate wear resistance and tool life for several grades. The experimentation also examined the effects of varying the relative proportions …

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Service Supply Chain Management : A Hierarchical Decision Modeling Approach, Roger Angel Solano-Cayama Aug 2008

Service Supply Chain Management : A Hierarchical Decision Modeling Approach, Roger Angel Solano-Cayama

Dissertations

A Service Supply Chain (SSC) may be described as a network of service provider facilities (in-house or outsourced), each of which is able to process one or more service tasks on an as needed basis. Two key characteristics of a SSC are (i) the business service is decomposable into several sequential tasks that can be processed by different service providers, and (ii) the primary capacity resource is skilled labor. SSCs are increasingly being developed by companies that experience a high variability of demand for their services (e.g., loan processing, analytical consulting services, emergency repair crews, claims processing, etc.). Typically, the …

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Modeling Systems For Optimal Resource Allocation, Scheduling, And Decision Making, Esengul Tayfur Aug 2008

Modeling Systems For Optimal Resource Allocation, Scheduling, And Decision Making, Esengul Tayfur

All Dissertations

This dissertation focuses on the resource requirements and scheduling problem for logistic systems. We investigate solutions to this problem in two different logistic systems: logistic system of the health care facilities during emergency evacuations and delivery and distribution system of production industries. All hospitals must have an evacuation plan to ensure the safety of patients and prevent the loss of life. However, hospital operators have not been able to quantify how resource availability, the cost of acquiring those resources, and evacuation completion time are related. This research addresses this problem and contributes two methodologies to solve this problem. In the …

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Revenue And Order Management Under Demand Uncertainty, Kiran Chahar Aug 2008

Revenue And Order Management Under Demand Uncertainty, Kiran Chahar

All Dissertations

We consider a firm that delivers its products across several customers or markets, each with unique revenue and uncertain demand size for a single selling season. Given that the firm experiences a long procurement lead time, the firm must decide, far in advance of the selling season not only the markets to be pursued but also the procurement quantity. In this dissertation, we present several operational scenarios in which the firm must decide which customer demands to satisfy, at what level to satisfy each customer demand, and how much to produce (or order) in total.
Traditionally, a newsvendor approach to …

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Strategic Plan For Industrial And Management Systems Engineering, Paul Savory Aug 2008

Strategic Plan For Industrial And Management Systems Engineering, Paul Savory

Department of Industrial and Management Systems Engineering: Reports

The role of this strategic plan is to map out a range of department goals, offer objectives for achieving each goal, and list potential strategies for meeting an objective. It also lists performance metrics for measuring progress for each goal. Each year, a subset of goals and objectives will be identified by the IMSE department as a priority for the coming year. Detailed metrics for measuring improvement for the department’s priorities areas will then be defined. The department committee to develop the plan consisted of Paul Savory (committee chair), Susan Hallbeck, and Erick Jones.

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Randomly Generating Manufacturing Flow Line Models Using Mathematica, Paul Savory Jul 2008

Randomly Generating Manufacturing Flow Line Models Using Mathematica, Paul Savory

Department of Industrial and Management Systems Engineering: Faculty Publications

To test heuristic algorithms and techniques, researchers need numerous datasets so as to measure effectiveness and improve approaches. This paper discusses using Mathematica, a mathematical programming language, for randomly generating the specifications for manufacturing flow line models. Important issues include determining an arrival rate to a flow line, the number of flow line stations, the number of parallel servers for each production station, and specifying the service time distributions and their associated parameters. The paper concludes with a discussion on generating more general types of simulation models.

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Modeling Of A Spray Assisted Natural Draft Cooling Tower, Kaunde K Jun 2008

Modeling Of A Spray Assisted Natural Draft Cooling Tower, Kaunde K

Tanzania Journal of Engineering and Technology (TJET)

Cooling towers are one of the largest heat and mass transfer devices that are in common use. A novel type of cooling tower has been proposed in which air flow rate into the tower is drawn by ejector action of sprays instead of fans as is done in conventional mechanical forced or induced draft cooling towers. This novel design offers the potential of saving the energy cost for driving the fan. The paper presents mathematical models for momentum transfer which is the driving force causing the entrainment of air. Also the heat transfer model for co-current flow of liquid and …

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Application Of Non-Destructive Testing In Evaluating Reinforced Concrete Structural Elements In Buildings, I Rubaratuka Jun 2008

Application Of Non-Destructive Testing In Evaluating Reinforced Concrete Structural Elements In Buildings, I Rubaratuka

Tanzania Journal of Engineering and Technology (TJET)

Of recent a large number of existing reinforced concrete buildings have required reconstruction, renovation and improvement. This tendency poses a number of problems that have to be solved, the main one being to determine the actual strength condition of the structural components/elements of the building. It includes determination of the quality of materials used, specification of the types and description of apparent faults and damages and extent of wear of the building. To undertake this evaluation, non – destructive testing methods are used. In this paper, applications of non – destructive testing methods to determine the strength state of reinforced …

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Quality Control In The Construction Of Reinforced Concrete Buildings In Dar Es Salaam, I Rubaratuka Jun 2008

Quality Control In The Construction Of Reinforced Concrete Buildings In Dar Es Salaam, I Rubaratuka

Tanzania Journal of Engineering and Technology (TJET)

Quality Control in the construction industry is very important to ensure that what is being done conforms to the applicable standards or good practice and the contract documents. In this article, results of investigations conducted at different construction sites for reinforced concrete buildings in Dar es Salaam to check if quality control measures are being implemented are discussed. It has been established that generally quality control is not properly carried out. Finally, measures to enhance quality control on sites are outlined.

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Development Of A Genetic Algorithm Based Search Strategy Suited For Design Optimisation Of Internal Combustion Engines, Nalitolela G Jun 2008

Development Of A Genetic Algorithm Based Search Strategy Suited For Design Optimisation Of Internal Combustion Engines, Nalitolela G

Tanzania Journal of Engineering and Technology (TJET)

Engine design optimisation is a multi-objective, multi-domain problem in a discontinuous design space. The state of the art of optimisation techniques shows that only methods of direct and adaptive search are appropriate for this type of problem. These include, adaptive random search, simulated annealing, evolution strategies and genetic algorithms. Of these methods, the genetic algorithms have been shown to be the most suited for the optimisation of multi-modal response functions in a discontinuous design space. This paper considers the important characteristics of genetic algorithms and their adaptation for use in parametric design optimisation of internal combustion engines. In order to …

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Accuracy Analysis For Kolmogorov Entropy Used In Studying The Chaotic Dynamics Of Cfb Reactors Based On Solids Concentration Fluctuations, Samwel V. Manyele Jun 2008

Accuracy Analysis For Kolmogorov Entropy Used In Studying The Chaotic Dynamics Of Cfb Reactors Based On Solids Concentration Fluctuations, Samwel V. Manyele

Tanzania Journal of Engineering and Technology (TJET)

A study on the chaotic dynamics of a high flux circulating fluidized bed (CFB) riser (10-m high and 76-mm i.d.) using the maximum likelihood estimate of the Kolmogorov entropy (KML) is reported. The signals used were measured by using a solids concentration fiber optic probe, accuracy of which is reported based on statistical analysis. The sensitivity analysis of the parameters used for computing KML was conducted to identify optimum settings, based on the standard error, s(KML) and the nature of PDF of the b-values from the reconstructed phase space trajectories. The length of time series, N, sampling frequency, fs, and …

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Improving The Availability Of Manufacturability Information Through Decentralization Of Process Planning, Eliab Opiyo Jun 2008

Improving The Availability Of Manufacturability Information Through Decentralization Of Process Planning, Eliab Opiyo

Tanzania Journal of Engineering and Technology (TJET)

Process planning is part of the general product development and production process that usually follows design and precedes manufacturing. Manufacturability and process planning information in general play central role in many product development and production activities, including paradoxically, conceptual and detail design - the activities that take place before process planning. The need of conducting some of the process planning activities formally before or during design is thus rather obvious. One of the main research issues is therefore the identification of the process planning activities that can be performed before the traditional process planning phase and handling of the process …

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Strategies For Promoting The Use Of Concrete Pavements In Tanzania: Technical And Institutional Considerations, Mfinanga A Jun 2008

Strategies For Promoting The Use Of Concrete Pavements In Tanzania: Technical And Institutional Considerations, Mfinanga A

Tanzania Journal of Engineering and Technology (TJET)

High-type roads in Tanzania have been predominantly of asphaltic concrete construction. This ever enlarging and ageing asphaltic road network represents increasing resource requirements on the road agency in the form of maintenance. Limited resources coupled with the ever sky-rocketing costs of petroleum products and the competing demands of social economic developments, presupposes the need to look for alternative road construction technology that is more cost-effective and resource optimising. Experience gained from developed and some developing countries where concrete pavements have been widely used suggests the potential of this type of pavement in many developing countries. This paper discusses the technical …

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A Project-Based Electronics Manufacturing Laboratory Course For Lower-Division Engineering Students, Jianbiao Pan, Albert Liddicoat, James G. Harris, Dominic Dal Bello Jun 2008

A Project-Based Electronics Manufacturing Laboratory Course For Lower-Division Engineering Students, Jianbiao Pan, Albert Liddicoat, James G. Harris, Dominic Dal Bello

Industrial and Manufacturing Engineering

This paper presents a project-based laboratory course on electronics design and manufacturing. The goal of this course is to provide lower-division engineering students a hands-on experience involving actual printed circuit board (PCB) design, layout, fabrication, assembly, and testing. Through project-based learning, students not only learn technical skills in designing and manufacturing an electronic device, but also develop their project management and communication skills early in their course of study at the university. The course outline and examples of the student projects are presented in this paper as well as project evaluations and students’ feedback. This paper also presents the selection …

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Curricular Enhancement To Support Project-Based Learning In Computer And Electrical Engineering, Albert Liddicoat, Jianbiao Pan, James G. Harris, Lynne A. Slivovsky Jun 2008

Curricular Enhancement To Support Project-Based Learning In Computer And Electrical Engineering, Albert Liddicoat, Jianbiao Pan, James G. Harris, Lynne A. Slivovsky

Industrial and Manufacturing Engineering

Undergraduate computer and electrical engineering programs often partition the curriculum into several courses based on related topics taught in isolation. Students are expected to synthesize their knowledge in a senior design project. It is the authors’ experience that students often struggle during their senior design project since they have not gained the appropriate knowledge or mastered necessary skills needed to work on a significant or team-based engineering design project. Specifically, students need to be able to define system requirements, partition the design into subcomponents, design, build, test, and verify that the system requirements have been met. The authors have enhanced …

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Enhancing Student Learning Through State-Of-The-Art Systems Level Design And Implementation: The Development Of A Lower Division Learning Module, James G. Harris, Dominic Dal Bello, Jianbiao Pan, Albert Liddicoat Jun 2008

Enhancing Student Learning Through State-Of-The-Art Systems Level Design And Implementation: The Development Of A Lower Division Learning Module, James G. Harris, Dominic Dal Bello, Jianbiao Pan, Albert Liddicoat

Industrial and Manufacturing Engineering

The Cal Poly/Allan Hancock team is developing a learning module that will allow all lower division engineering students to design, fabricate, assemble, and test an electronic system implemented on a printed circuit board (PCB). All the services necessary to perform this laboratory experiment will be provided with low-cost vendors available on the . The learning module is being developed so that it can be integrated into the existing electrical engineering lower division courses that are required by all engineering students. The laboratory learning module will use operational amplifiers (op amp), resistors, capacitors and other common electronic components to study the …

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