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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An empirical analysis of automotive manufacturers' supply chain performance in China

Ling, Wan January 2011 (has links)
The research develops a framework for the evaluation of automotive supply chain performance in China. In addition, the research presents indications from a study of Chinese automotive companies with regards to their evaluation and attempts to propose some alternatives for future improvement.
2

Measurement of Electrostatic Dipoles and Net Charge on Air Dispersed Particles

Bagga, Payel January 2009 (has links)
Dipoles are expected to often dramatically enhance the mutual collision rate of diffusing particles (above the effects of Brownian or turbulent motion). However, this spreading awareness of the possible influence of discrete dipoles on particles is still based largely on theory, and some qualitative experience of particle behaviour from microgravity experiments. Individual particle dipoles have not yet been definitely isolated in experiments, nor measured in practical situations. In this project, it was intended to measure, for the first time, distributions of dipole strength (as well as net charge and particle size) on particulates dispersed into air by typical industrial and pharmaceutical processing methods. The instruments designed to do this were built around a sampling head which allowed examination of a flow of dust dispersed into an air stream. During dispersal, the particles suffered tribocharging by mutual separation and collision on walls. Examination of the particles involved recording the path of particles as they moved through a non-uniform electric field around a central electrode, which was supplied with high voltage. Particles were attracted towards the central electrode (of 0.5 mm diameter in this study) if they contained dipoles, independent of the polarity of the field or their net charge. Particles to be examined were illuminated by a laser sheet as they moved past, and a high speed video captured their trajectories (over a field of view of around 5 mm). The equation of motion of a particle which involved the forces of both particle net charge and dipole strength was applied to the particle path to evaluate both these parameters. The particle trajectories were modelled, and checked against the observed experimental trajectories. The voltage applied to the probe varied from 4 kV to 18 kV but for most of the runs 6 kV voltage was used. The electric field around the probe tip was assumed to be same as that for a spherical electrode of the same size as the probe. The flow field axially towards and around the probe tip was calculated using the Stokes creeping flow equations around a sphere. The calculated electric and flow fields were checked against COMSOL Multiphysics models applied to actual geometries and flow regimes. The rotation dynamics of the particles was also considered important in the technique, requiring possibly extra knowledge of the initial direction of the dipole. The flow was led through a lateral field between two plates in order to orient the direction of any dipoles in the direction of the lateral field. The expected orientation of dipoles coming out of the plates was used as an initial guess of their orientation for modelling the rotation of the dipoles when they entered the probe field. Misalignment after leaving the plate field and before entering the probe field was also considered, and was found to be important due to vortices characterised by smoke and particle studies. However, the trajectory modelling revealed that the particles studied quickly rotated into alignment with the probe field, providing maximum attractive force to the probe, and so the values of net charge and dipole strength obtained did not depend on the initial orientation. Estimated errors of particle position and diameter used in all the calculation steps were judged to be well within a basic image error limit of ±1 pixel. Some particle trajectories showed unexplainable shapes which was traced to the influence of large mixing eddies around the gas/particle jet. A check for corona discharge at the probe tip was made both at the beginning and at the end of the sampling experiments. No corona was detected initially (up to 18 kV), but a discharge could be observed at voltages close to 7 kV in the later checks. Particles of acrylic, glass bubbles, whole milk and fertiliser powder were sampled and net charges and dipole charges were estimated. The sampled particles overall had net charge and dipole charge in the range of 10-15 C to 10-12 C on individual particles with diameters 20 μm -130 μm. Dipoles were more evident (more easily measured) for glass bubbles but the presence of dipoles on other particle samples was found and could not be completely ruled out for many of them. The analysis procedure is presently time consuming but can be automated so it is recommended in the future that it should be automated. The work can be extended into industrial situations by sampling moving dust suspensions, e.g. fluid bed overflows and pneumatically conveyed outflows, useful in the dairy and fertilizer industries.
3

Internal communication in B2B context : A case study at Electrolux

Hansson, Marcus, Blomqvist, Patrik January 2014 (has links)
Effective internal communication is an important factor for organizational success. Organizations need to evaluate and improve their internal communication especially in an increasingly difficult and competitive economic environment. In this regard, measurement instruments enable organizations to monitor communication effectiveness of internal communication systems (Ruck & Welch, 2012). The focus for this study will be the concept of internal communication within an organization. In order to establish and identify the purpose of the study a literature review was        performed that examined the existing research within the field.The purpose of this study is to investigate the factors that influence the effectiveness of internal communication from the employee perception at the logistic department of Electrolux. Three research questions were then conducted in order to answer the purpose. The study has been conducted through a case study in the form of in-depth interviews. The study was carried out through 11 interviews with employees from the logistic department of Electrolux Laundry System AB in Ljungby. In the current business environment a formal way of strategically handle the              communication that is practiced within an organization is needed in relation to higher competitive advantage. The study reveals that Electrolux logistic center is not practicing this in any higher degree in accordance to the theory of effective communication. No clear goal regarding communication or measuring communication was identified. In accordance to this practical managerial implication was concluded based on these findings. The presented research model done was suggested to be developed as a further research
4

Testing and Packaging for MEMS Acoustic Emission Sensors

Liu, Ting-Hung 21 June 2018 (has links)
The goal of this research is to improve the structure and dimension of the MEMS acoustic emission sensor. Acoustic emission sensor (AE sensor) based on the piezoelectric transducer is a well-developed technology in non-destructive testing that is widely used to determine permanent damage such as cracks and corrosions in buildings and structures. The AE sensor can be used to monitor cracks in structures and to check leakage in pressurized systems. The location of cracks in a structure or system leakage causes a high-frequency surface vibration while releasing ultrasonic energy. The frequency of this energy is typically between 30 kHz to 1MHz. The AE sensor can detect this high frequency transient acoustic wave. By using this AE sensor, the structure and pressurized system can be monitored to generate an evaluation report in order to facilitate maintenance and structure repair. Currently, the commercial AE sensor is bulky because it is made of a piezoelectric transducer. It also needs a lot of wires to connect with the pre-amplifier and signal conditioning systems. Because of the cost, brittleness and the volume of the commercial AE sensor, new affordable AE sensor technology is desired to replace the commercial AE sensor. The new AE sensor should be economical, small, and lightweight. The performance of the output signal should be comparable with the commercial AE sensor in terms of signal strength and signal to noise ratio. The MEMS AE sensors provide the potential solution to this problem. The MEMS AE sensors can overcome the problems of the commercial AE sensor. The MEMS AE sensor combines the pre- amplifier on the chip in a single package. Through the MEMS technology, the AE sensor can be manufactured in mass quantity and high quality. This study focuses on simulating and measuring the performance of the MEMS acoustic emission sensors. Through simulation, the capacitance value is influenced by the gap between the suspended membrane (top perforated metal plate), metal ground, and also influenced by the effective area of the perforated top layer. The perforation is introduced to reduce the squeeze film damping effect. Through measurement verification, the MEMS AE sensors have exhibited comparable performance before and after inclusion of the 3D printed package that serves as the housing for the completed sensor assembly. The C-V measurement is the key method to extract the capacitance value, which is the key parameter to determine the signal strength and signal to noise ratio for capacitive MEMS acoustic emission sensors. The damping coefficient is also the key factor to receive the time domain measurement data in a fashion that resemble the bulky commercial piezoelectric AE transducers.
5

Electrical Resistance and Acoustic Emission Measurements for Monitoring the Structural Behavior of CFRP Laminate

Zhou, Wei 12 July 2015 (has links)
Electrical resistance and acoustic emission (AE) measurement are jointly used to monitor the degradation in CFRP laminates subjected to tensile tests. The objective of this thesis is to perform a synergertic analysis between a passive and an active methods to better access how these perform when used for Structural Health Moni- toring (SHM). Laminates with three different stacking sequences: [0]4, [02/902]s and [+45/ − 45]2s are subjected to monotonic and cyclic tensile tests. In each laminate, we carefully investigate which mechanisms of degradation can or cannot be detect- ed by each technique. It is shown that most often, that acoustic emission signals start before any electrical detection is possible. This is is explained based on the redundance of the electrical network that makes it less sensitive to localized damages. Based on in depth study of AE signals clustering, a new classification is proposed to recognize the different damage mechanims based on only two parameters: the RA (rise time/amplitude) and the duration of the signal.
6

Improvements to Whole Lens Reconstruction for Saline Submerged Soft Contact Lenses

Guido, Christopher James January 2016 (has links)
A method for measuring the thickness and surface profiles of soft contact lenses while submerged in a saline solution has been implemented utilizing a low coherence Twyman-Green Interferometer. Although the original measurements demonstrated that features on the contact lens surfaces could be accurately determined, it was believed that the layout of the system also induced surface profile distortions. A new opto-mechanical layout has been implemented which eliminates many of these low frequency distortions. Improvements to the original phase unwrapping algorithms have also been developed to overcome the low visibility output inherent to the measurement allowing for a more complete analysis of the two surfaces of a contact lens.
7

SIGNAL INTEGRITY ANALYSIS ON MATERIALS AND VIA STRUCTURES MODELING AND CHARACTERIZATION

Li, Qian. January 2011 (has links)
The development of modern digital communication systems has been entered a new era with faster signal transmission and processing capability, called high-speed circuit systems. As their clock frequencies have increased and rise times of signals have decreased, the signal integrity of interconnects in the packaging and printed circuit boards plays a more and more important role. In high-speed circuit systems, the well-designed logic functions most likely will not work well if their interconnects are not taken into account.This dissertation addresses to profoundly understand the signal integrity knowledge, be proficient in calculation, simulation and measurements, and be capable of solving related signal integrity problems. The research mainly emphasizes on three aspects. First of all, the impact of on-wafer calibration methods on the measured results of coplanar waveguide circuits is comprehensively investigated, with their measurement repeatability and accuracy. Furthermore, a method is presented to characterize the physically-consistent broadband material properties for both rigid and flexible dielectric materials. Last but not least, a hybrid method for efficient modeling of three dimensional via structures is developed, in order to simplify the traditional 3D full-length via simulations and dramatically reduce the via build and simulation time and complexity.
8

Functional measurement of immunization decision making

Pingenot, Alleene M. January 1900 (has links)
Doctor of Philosophy / Department of Psychology / James C. Shanteau / Four variables from the HBM of healthcare behavior were used to examine immunization decision making by the lay public. Although there was evidence to support the HBM in general, results of these studies suggest that up to 70% of the variance in immunization decision-making could be explained by disease base rates alone. When there is a main effect of immunization side effects, this effect was entirely within the most severe category of side effect. In initial four experiments, there was a consistent interaction between the variable of disease type and the variables of disease severity and immunization side effects. The fifth experiment showed an interaction between disease type and immunization efficacy. Functional measurement was used to examine the nature of the interaction between the variables of disease base rates and immunization efficacy. This interaction is neither clearly additive nor multiplicative. Disease base rate dominates the other variables, although each modifies immunization likelihood somewhat in interaction with disease base rates. Furthermore, results suggest that participants did not appear to react to the difference between different disease base rates when the probabilities are small. Participants also did not conceptualize immunization efficacy as a conditional probability. Suggestions for how to address these issues via decision support were made. The principle contribution of this study, however, is development of a methodology. The method developed here investigates the variables of the HBM in an ecologically valid factorial design. This approach takes the HBM beyond description of variables to provision of prediction and generalizable results.
9

Automatické rozměření vícesvodových EKG signálů / Automatic Delineation of Multi-lead ECG Signals

Veverka, Vojtěch January 2017 (has links)
This semester thesis is focused on automated measurement of ECG signal. The theoretical part describes the rise and options ECG signal. Furthermore, the issue is staged principal components analysis, whose output is used as input signal for seasons. They describe the basic methods used in measurement to ECG signal. The practical part is designed in measurement algorithm for ECG signal that has been tested on basic CSE database. The results are discussed in the conclusion.
10

Constitutive compatibility based identification of spatially varying elastic parameters distributions

Moussawi, Ali 12 1900 (has links)
The experimental identification of mechanical properties is crucial in mechanics for understanding material behavior and for the development of numerical models. Classical identification procedures employ standard shaped specimens, assume that the mechanical fields in the object are homogeneous, and recover global properties. Thus, multiple tests are required for full characterization of a heterogeneous object, leading to a time consuming and costly process. The development of non-contact, full-field measurement techniques from which complex kinematic fields can be recorded has opened the door to a new way of thinking. From the identification point of view, suitable methods can be used to process these complex kinematic fields in order to recover multiple spatially varying parameters through one test or a few tests. The requirement is the development of identification techniques that can process these complex experimental data. This thesis introduces a novel identification technique called the constitutive compatibility method. The key idea is to define stresses as compatible with the observed kinematic field through the chosen class of constitutive equation, making possible the uncoupling of the identification of stress from the identification of the material parameters. This uncoupling leads to parametrized solutions in cases where 5 the solution is non-unique (due to unknown traction boundary conditions) as demonstrated on 2D numerical examples. First the theory is outlined and the method is demonstrated in 2D applications. Second, the method is implemented within a domain decomposition framework in order to reduce the cost for processing very large problems. Finally, it is extended to 3D numerical examples. Promising results are shown for 2D and 3D problems

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