This thesis has two goals. First, we analyze the stresses in the conveyor belt system to... ]]> Zhan Zhang http://iris.lib.neu.edu/mech_eng_theses/69 http://iris.lib.neu.edu/mech_eng_theses/69 Wed, 10 Apr 2013 09:49:50 PDT The ability to control the ankle muscles and produce adequate range of motion in the ankle joints are key components of gait and balance function. Patients who suffer from neurological impairments, such as stroke or traumatic brain injury, frequently lose gait and balance function due in part to loss of ankle control. Described in this thesis is a unique two degree of freedom (DOF) mechatronic device with a virtual reality interface that has been developed to meet the needs of such patients for ankle and balance rehabilitation. The Northeastern University Virtual Ankle and Balance Trainer (NUVABAT) rehabilitation system has five... ]]> Ye Ding http://iris.lib.neu.edu/mech_eng_theses/68 http://iris.lib.neu.edu/mech_eng_theses/68 Tue, 09 Apr 2013 09:29:59 PDT Small tin spheres, approximately 100 µm in diameter or less, can be used in high-performance electronics packaging applications, and therefore need to be produced to high levels of uniformity. The lead-free, tin-based alloy SN100C is of particular interest as it can be used as a solder in such applications. The goal of this research was to determine the feasibility of the commercial production of tin and tin alloy spheres for industrial applications by the uniform droplet spray (UDS) process with multi-orifice designs. The alloy was ejected from a pressurized crucible through 25-µm orifices drilled in stainless steel, as well as... ]]> John Crum http://iris.lib.neu.edu/mech_eng_theses/67 http://iris.lib.neu.edu/mech_eng_theses/67 Wed, 03 Apr 2013 07:35:12 PDT In this Thesis, we focus on the analysis of driver lane-changing behavior based on the fact that lane changing is a ubiquitous driving maneuver in common driving environments and regarded as the most critical driving intention. Therefore, lane changing as a case study for driving intention recognition is introduced in this study. Our methodology is to employ machine learning method i.e., support vector machine, to the classification of driving intentions using vehicle performance data and driver eye gaze data from the measurement of the driving tasks (i.e., lane following and lane changing) in the well-designed simulation environment. To improve recognition... ]]> Xianyi Huang http://iris.lib.neu.edu/mech_eng_theses/66 http://iris.lib.neu.edu/mech_eng_theses/66 Thu, 07 Mar 2013 07:23:07 PST The amounts of waste plastics discarded in developed countries are increasing drastically, and most are not recycled. The small fractions of the post-consumer plastics which are recycled find few new uses as their quality is degraded; they cannot be reused in their original applications. However, the high energy density of plastics, similar to that of premium fuels, combined with the dwindling reserves of fossil fuels make a compelling argument for releasing their internal energy through combustion, converting it to thermal energy and, eventually, to electricity through a heat engine. To minimize the emission of pollutants this energy conversion is done... ]]> Saber Talebi Anaraki http://iris.lib.neu.edu/mech_eng_theses/65 http://iris.lib.neu.edu/mech_eng_theses/65 Wed, 06 Mar 2013 09:25:52 PST Converting a lower driving frequency to a higher generating frequency has been shown to increase power outputs of low frequency vibrational energy harvesters. This approach, known as frequency up conversion, requires interaction between a lower resonant frequency element and a higher resonant frequency element. The interaction between the two elements can be based on impact or on non-contact interactions. Two forms of impact-based frequency up conversion for energy harvesters are coupled-motion harvesting and plucked harvesting. In coupled-motion harvesting, a driving beam impacts a generating beam. The beams then move together and energy is extracted primarily during the coupled-motion phase. In... ]]> Ryan St. Pierre http://iris.lib.neu.edu/mech_eng_theses/64 http://iris.lib.neu.edu/mech_eng_theses/64 Mon, 04 Mar 2013 08:56:56 PST This experimentation investigates the local heat transfer characteristics of an impinging jet with the effects of cross flow. The jet is formed by a single round hole with a diameter of 0.25 inches, sharp edges and a length to diameter ratio of 4. For one combination of impingement plate spacing and cross flow to jet flow mass velocity ratio, detailed photographs of a sheet of liquid crystal were taken. These photographs were then used to create a Nusselt number contour plot. Observations are made regarding the comparison of the Nusselt number contour plots with and without cross flow. Comparisons are... ]]> Brian Roberts http://iris.lib.neu.edu/mech_eng_theses/63 http://iris.lib.neu.edu/mech_eng_theses/63 Tue, 26 Feb 2013 13:46:19 PST Ultrasonic powder consolidation (UPC) is a novel rapid, full-density powder consolidation process in which metal powders confined in a die under uniaxial loading is subjected to ultrasonic vibration at low temperature for a few seconds or less. In this research, copper powders with dendritic and spherical morphologies and an aluminum powder with spherical morphology were subjected to UPC under various conditions to investigate the effects of the process variables on the densification and metallurgical bonding of the compact. An ultrasonic washing test, developed in this research, was used to determine the extent of densification and bonding achieved in specimens consolidated... ]]> Yangfan Li http://iris.lib.neu.edu/mech_eng_theses/62 http://iris.lib.neu.edu/mech_eng_theses/62 Tue, 19 Feb 2013 09:43:11 PST Turbine cooling technology plays a critical role in increasing the thermal efficiency and power output of advanced gas turbines. The common cooling methods include the impingement cooling method, the film cooling method, and the rib roughened cooling method. This study focuses on the impingement cooling effect on a rib roughened trailing edge channel with cross over holes and aims to find the influence of blocked exit holes to the heat transfer efficiency.

A steady state liquid crystal technique was used to get the heat transfer coefficient. In this experiment, two different kinds of cross over holes were used: five tilt... ]]> Xiao Huang http://iris.lib.neu.edu/mech_eng_theses/61 http://iris.lib.neu.edu/mech_eng_theses/61 Mon, 11 Feb 2013 08:43:31 PST Mechanical response and fracture of metal sandwich panels subjected to multiple impulsive pressure loads (shocks) were investigated for panels with honeycomb and folded plate core constructions. The structural performance of these panels to multiple impulsive pressure loads is quantified by the maximum transverse deflection of the face sheets and the core crushing strain at mid-span of the panels. A set of simulations was carried out to find the near-optimum core density of a square honeycomb core sandwich panels. The panels with a relative core density of 4-5% are shown to have minimum face sheet deflection under multiple shock loading, which... ]]> Hamid Ebrahimi http://iris.lib.neu.edu/mech_eng_theses/60 http://iris.lib.neu.edu/mech_eng_theses/60 Tue, 22 Jan 2013 12:47:07 PST Hand tremor is an involuntary muscle movement, trembling, or shaking of the hands. Caused by either essential tremor (ET) or Parkinson's disease, tremors often affect daily activities including feeding, drinking, typing, and writing. To reveal the design strategies to diminish effects of hand tremor in handheld devices, and in particular a drinking cup in this research, an experimental framework based on vibrations and dynamics has been developed with inspiration from the well-known gyroscopic boat stabilizers, i.e. Schlick stabilizers, in which a high speed rotating disk has been used as a source of angular momentum, producing a resistive gyroscopic torque when... ]]> Ehsan Abbaszadeh http://iris.lib.neu.edu/mech_eng_theses/59 http://iris.lib.neu.edu/mech_eng_theses/59 Tue, 16 Oct 2012 09:50:26 PDT In this study two imaging modalities are proposed as a basis for fracture analysis in bone; Computed Tomography (CT) and Positron Emission Tomography (PET).

In the first part of this study, finite element analysis (FEA); CT based structural rigidity analysis (CTRA) and mechanical testing are performed to assess the immediate fracture risk of rat tibia with simulated lytic defects at different locations.

Twenty rat tibia were randomly assigned to four equal groups (n=5). Three of the groups included a simulated defect at various locations: anterior bone surface (Group 1), posterior bone surface (Group 2), and through bone defect (Group 3).... ]]> John Alexander Rennick http://iris.lib.neu.edu/mech_eng_theses/58 http://iris.lib.neu.edu/mech_eng_theses/58 Tue, 24 Jul 2012 09:22:15 PDT More advanced technology and materials in industry lead to the implementation of lightweight components in order for miniaturization and efficiency. Lightweight components and certain materials however, are susceptible to vibrations. The flexible structures that make up these systems pose a great problem for vibration control. The detailed modeling of such systems greatly reduces the complexity of the control law. It is this reason that an analysis of the model as a continuous system was done. The distributed-parameters system was then effectively reduced to an equivalent lumped-parameters model. The use of this discrete system was the basis for controller design of... ]]> Matthew Thomas Jamula http://iris.lib.neu.edu/mech_eng_theses/57 http://iris.lib.neu.edu/mech_eng_theses/57 Mon, 23 Jul 2012 10:22:34 PDT The effective life of a specimen is calculated as the time from when the specimen is in its operating conditions to the time of its failure and reliability indicates probability of survival of the specimen or product. In material science, this effective life is represented as the number of loading cycles until the failure of the specimen. Life of any product or specimen is inversely proportional to the load (stress or strain) applied on it. Practically, external loading is mostly fluctuating and various levels of loads are applied on the same specimen causing the specimen to fail over time and... ]]> Bharadwaj Sathiamoorthy http://iris.lib.neu.edu/mech_eng_theses/55 http://iris.lib.neu.edu/mech_eng_theses/55 Wed, 20 Jun 2012 06:10:23 PDT Electroactive Polymers (EAPs) have great potential to provide smart solutions to engineering problems in the fields such as robotics, medical devices, power generation, actuators and sensors. This is due to the fact that EAPs yield several important characteristics that are advantageous over conventional types of materials, like: lower weight, faster response, higher power density and quieter operation. In this thesis, the use of Dielectric Electroactive Polymer (DEAP) based actuators and sensors were studied in the following order: 1) Development of a nonlinear force control for PolyPower InLastor PUSH actuator, 2) Evaluation of the PUSH actuator for haptic use with respect... ]]> Muzaffer Yalgin Ozsecen http://iris.lib.neu.edu/mech_eng_theses/54 http://iris.lib.neu.edu/mech_eng_theses/54 Tue, 05 Jun 2012 12:08:02 PDT Polishing and erosion of aluminum surface using fluid jet carrying abrasive alumina particles was investigated. Setup was built and combined to a lathe allowing flexibility to vary jet orientation and control the jet impact location on the metal surface. The effects of pressure (90-75-50 psi), jet orientation (90°-60°-30°-15°) and polishing time (10-15-20 minutes) on the final surface obtained were studied. Experiments were carried out on a fixed spot on the aluminum substrate, keeping nozzle and substrate stationary. Stylus profilometry was used to examine the final surface along different directions. The surface morphology was investigated through measurements of depths and slopes... ]]> Shreyansh P. Patel http://iris.lib.neu.edu/mech_eng_theses/53 http://iris.lib.neu.edu/mech_eng_theses/53 Tue, 22 May 2012 06:19:34 PDT Introduction: Preparation of samples for electron microscopy typically balances the need to "fix" the sample against the necessary generation of artifacts which influence the interpretation of observed structures. Ultrarapid freezing by impact of a specimen with a thermally conductive metal surface, cooled to at least liquid nitrogen (LN) temperatures, has long been thought of as the gold standard for minimizing cryofixation artifact. However, there has been a long standing debate about whether or not impact with the metal surface introduces a mechanical deformation to the sample before it freezes. Though it has been argued that the mechanical deformation wave is... ]]> Nector Ritzakis http://iris.lib.neu.edu/mech_eng_theses/52 http://iris.lib.neu.edu/mech_eng_theses/52 Thu, 10 May 2012 07:39:06 PDT The unique properties of single domain magnetic nanoparticles have been studied since the 1950's. When a material is geometrically confined to nanoscale dimensions its characteristic properties can change dramatically. In this thesis the magnetic and magnetotransport characteristics of GaMnAs and MnAs nanostructured systems are explored in several novel experimental studies. The ternary magnetic semiconductor GaMnAs was investigated under 3 dimensions (3D) of spatial confinement.1 Up until this research, GaMnAs hadn't been successfully fabricated, or studied, as a nanodot. By creating a novel patterning approach using anodic porous alumina, the superparamagnetism of confined GaMnAs was able to be acquired using SQUID... ]]> Steven Bennett