Chinese students' trust in the safety of food purchased through online channels : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Safety Management at Massey University, Palmerston North, New Zealand

With the rapid development of E-commerce, online food shopping has become popular in the past decade in China. Considering the high level of concern that the Chinese have about food safety, there are questions around trust in the safety of food purchased online. The aim of this study is to analyse the factors influencing trust in food safety when Chinese university students purchase food via the internet. In order to examine the trust of Chinese university students in the safety of food purchased online, a survey was conducted on students from four Chinese universities in 2013. Data analysis was conducted on 1403 valid questionnaires. A Structural Equation Model, Principal Components Analysis and LISREL software were used as statistical tools for analysis. Trust in food safety is a dynamic process and is based on food risk information transfer. The main outcome of this study was the development of a multi-factor conceptual model of Chinese university students’ trust in the safety of food purchased online. This model consists of two separate determinants: food safety and the online shopping environment. Chinese university students were influenced more by the online shopping environment than by concerns with food safety. Trust in food safety is mainly influenced by two dimensions: Food Control (the general and constant element of trust) and Risk information (the changeable element of trust). Trust in the online shopping environment is influenced by two dimensions: Aesthetics and Functionality. Fourteen factors were found contributing to the trust in online food safety; traceability, media and delivery risk need more attention by industry. Since university students will become important online food shopping buyers when they graduate, New Zealand food industries that export to China should consider these factors that influence sales via the internet

Codebook Based Hybrid Precoding for Millimeter Wave Multiuser Systems

In millimeter wave (mmWave) systems, antenna architecture limitations make it difficult to apply conventional fully digital precoding techniques but call for low cost analog radio-frequency (RF) and digital baseband hybrid precoding methods. This paper investigates joint RF-baseband hybrid precoding for the downlink of multiuser multi-antenna mmWave systems with a limited number of RF chains. Two performance measures, maximizing the spectral efficiency and the energy efficiency of the system, are considered. We propose a codebook based RF precoding design and obtain the channel state information via a beam sweep procedure. Via the codebook based design, the original system is transformed into a virtual multiuser downlink system with the RF chain constraint. Consequently, we are able to simplify the complicated hybrid precoding optimization problems to joint codeword selection and precoder design (JWSPD) problems. Then, we propose efficient methods to address the JWSPD problems and jointly optimize the RF and baseband precoders under the two performance measures. Finally, extensive numerical results are provided to validate the effectiveness of the proposed hybrid precoders.Comment: 35 pages, 9 figures, to appear in Trans. on Signal Process, 201

Internet multimedia traffic classification from QoS perspective using semi-supervised dictionary learning models

To address the issue of finegrained classification of Internet multimedia traffic from a Quality of Service (QoS) perspective with a suitable granularity, this paper defines a new set of QoS classes and presents a modified K-Singular Value Decomposition (K-SVD) method for multimedia identification. After analyzing several instances of typical Internet multimedia traffic captured in a campus network, this paper defines a new set of QoS classes according to the difference in downstream/upstream rates and proposes a modified K-SVD method that can automatically search for underlying structural patterns in the QoS characteristic space. We define bag-QoS-words as the set of specific QoS local patterns, which can be expressed by core QoS characteristics. After the dictionary is constructed with an excess quantity of bag-QoS-words, Locality Constrained Feature Coding (LCFC) features of QoS classes are extracted. By associating a set of characteristics with a percentage of error, an objective function is formulated. In accordance with the modified K-SVD, Internet multimedia traffic can be classified into a corresponding QoS class with a linear Support Vector Machines (SVM) classifier. Our experimental results demonstrate the feasibility of the proposed classification method

Approximating the ground state eigenvalue via the effective potential

In this paper, we study 1-d random Schr\"odinger operators on a finite interval with Dirichlet boundary conditions. We are interested in the approximation of the ground state energy using the minimum of the effective potential. For the 1-d continuous Anderson Bernoulli model, we show that the ratio of the ground state energy and the minimum of the effective potential approaches $\frac{\pi^2}{8}$ as the domain size approaches infinity. Besides, we will discuss various approximations to the ratio in different situations. There will be numerical experiments supporting our main results for the ground state energy and also supporting approximations for the excited states energies