Incremental sheet forming process is a relatively new method of forming which is increasingly being used in the industry. Complex shapes can be manufactured using this method and the forming operation doesn't require any dies. High strains of over 300 % can also be achieved. Incremental sheet forming method is used to manufacture many different components presently. Prototype examples include car headlights, tubs, train body panels and medical products. The work done in the thesis deals with the prediction of the steady state forces acting on the tool during forming. Prediction of forces generated would help to design the machine against excessive vibrations. It would help the user to protect the tool and the material blank from failure. An efficient design ensures that the tool would not get deflected out of its path while forming, improving the accuracy of the finished part. To study the forces, experiments were conducted by forming pyramid and cone shapes. An experimental arrangement was set up and experimental data was collected using a data acquisition system. The effect that the various process parameters, like the thickness of the sheet, wall angle of the part and tool diameter had on the steady state force were studied. A three dimensional model was developed using commercial finite element software ABAQUS using a new modeling technique to simulate the deformation of the sheet metal blank during incremental sheet forming. The steady state forces generated for any shape, with any set of parameters used, could be predicted using the numerical model. The advantage of having a numerical model is that the forces can be predicted without doing experiments. The model was used to predict the steady state forces developed during forming of pyramid and cone shapes. The results were compared and were seen to be reasonably close to the experimental results. Later, the numerical model was validated by forming arbitrary shapes and comparing the value obtained from simulations to the value of the measured steady state forces. The results obtained from the numerical model were seen to match very well with the experimental forces for the new shapes. The numerical model developed using the new technique was seen to predict forces to a reasonable extent with less computational time as compared to the models currently available.

This thesis describes a new approach to accelerate the simulation of the steady-state response of nonlinear circuits using the Harmonic Balance (HB) technique. The approach presented in this work focuses on direct factorization of the sparse Jacobian matrix of the HB nonlinear equations using a Graphics Processing Unit (GPU) platform. This approach exploits the heterogeneous structure of the Jacobian matrix. The computational core of the proposed approach is based on developing a block-wise version of the KLU factorization algorithm, where scalar arithmetic operations are replaced by block-aware matrix operations. For a large number of harmonics, or excitation tones, or both the Block-KLU (BKLU) approach effectively raises the ratio of floating-point operations to other operations and, therefore, becomes an ideal vehicle for implementation on a GPU-based platform. Motivated by this fact, a GPU-based Hybrid Block KLU framework is developed to implement the BKLU. The proposed approach in this thesis is named Hybrid-BKLU. The Hybrid-BKLU is implemented in two parts, on the host CPU and on the graphic card’s GPU, using the OpenCL heterogeneous parallel programming language. To show the efficiency of the Hybrid-BKLU approach, its performance is compared with BKLU approach performing HB analysis on several test circuits. The Hybrid-BKLU approach yields speedup by up to 89 times over conventional BKLU on CPU.

BACKGROUND: Previous research has shown that the ventilatory threshold (VT) correlates highly with onset of lactate accumulation and maximal steady-state exercise (MSS) level. Also, studies have shown the VT is useful in prescribing exercise for cardiac patients in that it gives an exercise intensity at which the patient is metabolically stable. METHODS: The purpose of this study was to determine if a MSS response could be achieved at an exercise intensity corresponding to the VT for patients with CAD. A group of 31 patients with CAD performed a maximal effort treadmill exercise test in which respiratory gas exchange was measured. The VT was determined using the V-slope method of computer regression analysis of the plot of carbon dioxide production versus oxygen consumption. Subjects then performed a constant load treadmill test a speed and grade that corresponded to the VT. Heart rate (HR), systolic blood pressure (SBP), and rating of perceived exertion (RPE) evaluated for steady-state responses. If subjects showed a steady-state response in two of these three parameters they were scored as having achieved a maximal steady-state (MSS+) response; those not meeting this standard were scored as failing to achieve maximal steady-state (MSS-) response. Subjects were analyzed as an entire group (N=31), as well as analyzed in subsets according to history of myocardial infarction (MI+, N=20; MI-, N=11) and administration of beta-blocker medications (BB+, N=16; BB-, N=15). RESULTS: Overall, subjects demonstrated significantly more MSS+ responses than MSS- responses (80% Vs 20%, P<0.05). Analysis of the subgroup data showed that it was the patient s with a history of MI (MI+ =85%, P<0.05) and those not receiving beta-blocker medications (BB- = 93%, P<0.05) who had significantly greater proportions of subject achieving MSS+ responses in the fixed load exercise condition. Conversely patient in the MI- (73 %, P < 0.05) and BB (69% P < 0.05) groups showed no significant differences in the number of MSS+ and MSS- responses. CONCLUSIONS: The VT, as measured during ramp exercise testing on the treadmill, provided a basis for establishing a maximal steady-state load in terms of cardiovascular and perceptual variables for 80% of the patients in the CAD study group. The measurements of HR, SBP, and RPE are easily obtained in a clinical setting and thus enable the VT to be used in bringing about a more efficacious exercise prescription. The validity of this method may be questioned, however, for patient with out a history of MI and for those receiving beta-blocker medications. / Master of Science

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Yes / Desalination has become one of the obvious solutions for the global water crisis due to affording high-quality water from seawater and brackish water resources. As a result, there are continuing efforts being made to improve desalination technologies, especially the one producing high-quantity freshwater, i.e., thermal desalination. This improvement must be accomplished via enhancement of process design through optimization which is implicitly dependent on providing a generic process model. Due to the scarcity of a comprehensive review paper for modeling multi-effect distillation (MED) process, this topic is becoming more important. Therefore, this paper intends to capture the evolution of modeling the forward feed MED (most common type) and shed a light on its branches of steady-state and dynamic modeling. The maturity of the models developed for MED will be thoroughly reviewed to clarify the general efforts made highlighting the advantages and disadvantages. Depending on the outputs of this review, the requirements of process development and emerging challengeable matters of modeling will be specified. This, in turn, would afford a possible improvement strategy to gain a reliable and sustainable thermal desalination process.

<p> Steady state heat and mass balancing around an ethylene/ethane distillation unit at Polymer Corporation, Sarnia is studied using the CHESS simulation executive system.</p> <p> The unit involves a single column with reboiler heat provided by recompression of the overhead vapor stream.</p> <p> A new column model is developed, based on the approximate pseudo-binary method of Hengstebeck, and is shown to give good results with marked savings in computation time over the conventional tray to tray methods. Models for vapor compression and heat exchange are also presented.</p> <p> The system model is fitted to plant data and a routine developed to obtain satisfactory system convergence.</p> <p> A parametric study is carried out in which column pressure and distillate product enthalpy are varied to demonstrate significant improvements in plant operation.</p> <p> An evaluation of the CHESS simulation system is presented.</p> / Thesis / Master of Engineering (MEngr)

<p> Steady state response of a single degree of freedom system with impact damper, with the main emphasis of two impacts (symmetric or unsymmetric)/cycle motion, and its asymptotic stability criterion are derived analytically. Stability regions are determined for wide range of parameters of the impact damper by using digital computer. </p> <p> Experimental study is also made to verify the assumptions taken in the analytical solution and to obtain general response of the system for wide range of parameters of the impact damper. </p> <p> As a result, it is found that unsymmetric two impacts per cycle motion exists and is stable for a wide range of parameters of the impact damper. </p> <p> Also, it is found that three and four impacts/cycle motions exist and are stable. </p> <p> Stability boundaries are found to be a complicated function of the impact damper parameters. </p> / Thesis / Master of Engineering (MEngr)

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