This dissertation examines issues related to avian influenza (AI) disease. This is done via three essays that individually examine: (1) the impacts of climate change on the probability and expected numbers of AI outbreaks and associated economic loss; (2) the effects that media coverage of AI outbreaks has on meat demand in the United States, and (3) the potential effectiveness of AI mitigation strategies on poultry production and welfare under a simulated AI outbreak in United States. The climate change and spread of AI outbreaks study finds that the probability and expected number of AI outbreaks increases as climate change proceeds. Particularly, past climate change has contributed to the current spread of AI disease by 11% and the future climate change will increase this spread by another 12%. Moreover, the underreporting probability of AI outbreaks is also examined and results show that the underreporting probability is much higher in countries with lower gross domestic production level, larger export of poultry products and more numbers of AI confirmed human deaths. Therefore, disease prevention and control plans should focus on these economically poor and climatically changed regions. AI outbreak information has significant effects on meat demand in the United States. In particular, impacts of overseas AI human deaths on meat demand equal 0.02% for beef, -0.005% for pork, and -0.01% for chicken for sample when there was no AI occurred in the United States, while it has smaller impacts on meat expenditure when using the whole sample. In addition, human deaths due to AI disease will increase beef demand and decrease that for pork and chicken. However, AI media coverage in short-run has insignificant effect on meat demand, which suggests that consumers are more cautious when cases occur within the United States as opposed to international cases. In the study on the effects and welfare implications of AI mitigation strategies, results find that vaccination strategy is welfare decreasing under most cases of demand shocks but is desirable in some regions when both domestic and excess demand decrease. Under the assumption of one AI outbreak in the United States, the associated mitigation costs because of past climate change are relatively small.

I den här studien analyseras hur Kinas konsumtion av olja påverkas av förändringar i oljepris och inkomst. Resultat visar att deras konsumtion av olja i förhållande till BNP per capita är relativt låg samt att deras fordonskoncentration är låg. År 2004 konsumerade Kina 14 procent mindre olja per capita än vad genomsnittligt land gör vid samma BNP per capitanivå. Fordonskoncentration år 2003 var 25 fordon per 1000 invånare, denna studie visar att om de hade haft en genomsnittlig fordonskoncentration skulle denna siffra varit 40 samma sätt till att vara på Deras ovan nämnda relativt låga fordonskoncentration och konsumtion av olja, kan peka mot att en fortsatt konsumtionsökning. År 2004 var den globala konsumtionen av olja i genomsnitt 81 miljoner fat dagligen (mb/d) och Kinas uppgick till 6.7 mb/d (BPstats ). Ett antal prognoser finns gjorda angående Kinas framtida konsumtion av olja. Enligt EIA 2005, kommer den att uppgå till 12.3 mb/d år 2020 och enligt IEA 2005 till 11.2 mb/d år 2020. Den empiriska undersökningen i denna studie belyser med signifikanta resultat hur Kinas konsumtion av olja påverkas utav pris- och inkomstförändringar. De ekonometriska resultaten i denna studie indikerar att deras konsumtion av olja är mer känslig för inkomst- än prisförändringar. Den långsiktiga inkomstelasticiteten uppmättes i den här studien till 1.317 och den långsiktiga priselasticiteten till -0.633. Med hänvisning till detta och ceteris paribus, kan en inkomstökning på 100 procent över perioden 2005-2020 leda till att Kina år 2020 konsumerar 17.6 mb/d. Således kan prognoserna från EIA (2005) och IEA (2005) vara underestimerade. De inkomst- och priselasticitet som är estimerade i denna studie konfirmerar Dargay och Gatelys resultat från 1994 att ett mindre utvecklat lands konsumtion av olja påverkas mer av förändringar i inkomst än i pris.

According to OECD statistics, products categorised as electronic machinery equipment (EME) has experienced the highest export growth in China from 1992-2003. Thus, the sec-tor encounters not only a great importance for Chinese export in absolute figures, its high growth during recent years may also imply a great importance for the future. The purpose of this thesis was to compose an export demand equation for Chinese Elec-trical machinery equipment, examining how Relative prises, GDP in importing country, distance to importing country, and the importing countries FDI in China affects foreign demand in this sector. The empirical test indicates that the variables included in this analy-sis can be used to explain foreign demand for Chinese produced EME. As in accordance to theory importers GDP and FDI was found to have a significant posi-tive affect on EME export, likewise distance was found to influence the EME export nega-tively. Unexpectedly, Relative price (Pc/Pw) seemed to have a positive effect on EME ex-port. This implausible finding may be caused by quality heterogeneity of products included in the EME sector and the large proportion of intermediate products incorporated in Chi-nese EME export. / Enligt statistik från OECD så har produkter klassificerade inom området ”utrustning för elektroniska maskiner” redovisat den högsta exporttillväxten i Kina under 1992-2003. Denna sektor är därför inte bara viktig för den kinesiska ekonomin i absolut tal utan den starka tillväxten under de senaste åren är även viktig för den framtida kinesiska exporten. Syftet med den här uppsatsen är att formulera en efterfrågefunktion för produkter inom sektorn ”utrustning för elektroniska maskiner”. Uppsatsen undersöker hur relativa priser, importlandets BNP, geografiskt avstånd till importlandet samt hur importlandets direktin-vesteringar i Kina påverkar efterfrågan av produkter inom den valda sektorn. De utförda empiriska testerna bevisar att dessa variabler kan användas för att förklara efterfrågan av kinesiska produkter inom den valda sektorn. Denna uppsats visar att en ökning av exportlandets BNP eller direkt investeringar i Kina påverkar exporten inom den valda sektor positivt. Det geografiska avståndet mellan Kina och importlandet redovisade en negativ påverkan av exporten av produkter inom den valda sektorn. Relativa priser (Pc/Pw) redovisade tydliga positiva effekter på exporten inom sek-torn. Detta något oväntade resultat orsakades sannolikt av heterogeniteten inom den valda sektorn samt den höga andel av intermediära produkter som inkluderas inom sektorn.

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This thesis studies a single item periodic review inventory problem with stochastic demand, random price and quotation cost. It differs from the traditional inventory model in that at the beginning of each period, a decision is made whether to pay the quotation cost to get the price information. If it is decided to request a price quote then the next decision is on how many units to order; otherwise, there will be no order. An (r, S1, S2) policy with r < S2, S1 <= S2 is proposed for the problem with two prices. It prescribes that when the inventory is less than or equal to r, the price quotation is requested; if the higher price is quoted, then order up to S1, otherwise to S2. There are two cases, r < S1 or S1 <= r. In the first case, every time the price is quoted, an order is placed. It is a single reorder point two order-up-to levels policy that can be considered as an extension of the (s, S) policy. In the second case, S1 <= r, it is possible to “request a quote but not buy” if the quoted price is not favorable when the inventory is between S1 and r. Two total cost functions are derived for the cases r < S1 <= S2 and S1 <= r < S2 respectively. Then optimization algorithms are devised based on the properties of the cost functions and tested in numerical study. The algorithms successfully find the optimal policies in all of the 135 test cases. Compared to the exhaustive search, the running time of the optimization algorithm is reduced significantly. The numerical study shows that the optimal (r, S1, S2) policy can save up to 50% by ordering up to different levels for different prices, compared to the optimal (s, S) policy. It also reveals that in some cases it is optimal to search price speculatively, that is with S1 < r, to request a quote but only place an order when the lower price is realized, when the inventory level is between S1 and r.

Previous research has developed a number of efficient protocols for streaming popular multimedia files on-demand to potentially large numbers of concurrent clients. These protocols can achieve server bandwidth usage that grows much slower than linearly with the file request rate, and with the inverse of client start-up delay. This hesis makes the following three main contributions to the design and performance evaluation of such protocols. The first contribution is an investigation of the network bandwidth requirements for scalable on-demand streaming. The results suggest that the minimum required network bandwidth for scalable on-demand streaming typically scales as K/ln(K) as the number of client sites K increases for fixed request rate per client site, and as ln(N/(ND+1)) as the total file request rate N increases or client start-up delay D decreases, for a fixed number of sites. Multicast delivery trees configured to minimize network bandwidth usage rather than latency are found to only modestly reduce the minimum required network bandwidth. Furthermore, it is possible to achieve close to the minimum possible network and server bandwidth usage simultaneously with practical scalable delivery protocols. Second, the thesis addresses the problem of scalable on-demand streaming of a more complex type of media than is typically considered, namely variable bit rate (VBR) media. A lower bound on the minimum required server bandwidth for scalable on-demand streaming of VBR media is derived. The lower bound analysis motivates the design of a new immediate service protocol termed VBR bandwidth skimming (VBRBS) that uses constant bit rate streaming, when sufficient client storage space is available, yet fruitfully exploits the knowledge of a VBR profile. Finally, the thesis proposes non-linear media containing parallel sequences of data frames, among which clients can dynamically select at designated branch points, and investigates the design and performance issues in scalable on-demand streaming of such media. Lower bounds on the minimum required server bandwidth for various non-linear media scalable on-demand streaming approaches are derived, practical non-linear media scalable delivery protocols are developed, and, as a proof-of-concept, a simple scalable delivery protocol is implemented in a non-linear media streaming prototype system.

Previous research has developed a number of efficient protocols for streaming popular multimedia files on-demand to potentially large numbers of concurrent clients. These protocols can achieve server bandwidth usage that grows much slower than linearly with the file request rate, and with the inverse of client start-up delay. This hesis makes the following three main contributions to the design and performance evaluation of such protocols. The first contribution is an investigation of the network bandwidth requirements for scalable on-demand streaming. The results suggest that the minimum required network bandwidth for scalable on-demand streaming typically scales as K/ln(K) as the number of client sites K increases for fixed request rate per client site, and as ln(N/(ND+1)) as the total file request rate N increases or client start-up delay D decreases, for a fixed number of sites. Multicast delivery trees configured to minimize network bandwidth usage rather than latency are found to only modestly reduce the minimum required network bandwidth. Furthermore, it is possible to achieve close to the minimum possible network and server bandwidth usage simultaneously with practical scalable delivery protocols. Second, the thesis addresses the problem of scalable on-demand streaming of a more complex type of media than is typically considered, namely variable bit rate (VBR) media. A lower bound on the minimum required server bandwidth for scalable on-demand streaming of VBR media is derived. The lower bound analysis motivates the design of a new immediate service protocol termed VBR bandwidth skimming (VBRBS) that uses constant bit rate streaming, when sufficient client storage space is available, yet fruitfully exploits the knowledge of a VBR profile. Finally, the thesis proposes non-linear media containing parallel sequences of data frames, among which clients can dynamically select at designated branch points, and investigates the design and performance issues in scalable on-demand streaming of such media. Lower bounds on the minimum required server bandwidth for various non-linear media scalable on-demand streaming approaches are derived, practical non-linear media scalable delivery protocols are developed, and, as a proof-of-concept, a simple scalable delivery protocol is implemented in a non-linear media streaming prototype system.

Power grids in today's developed societies are designed to meet consumer demands in a highly reliable manner. In order to guarantee reliability to consumers, the grid is required to be sized for infrequently occurring demand peaks. The cost of maintaining generation sources that make up the relatively unused capacity of the grid can be extremely high. In addition to high costs, environmental impacts of these sources are also of great concern. In order to serve highly fluctuating peak demands, energy sources such as coal, gas and bio-gas are commissioned by utilities. These sources have a high carbon footprint. In order to prevent wasting extensive amounts of money in maintaining infrequently used grid capacity and causing an adverse environmental impact, a comprehensive study on how elasticity of domestic appliances can be used to reduce the impact of these issues is made. A thorough analysis of appliances in four distinct regions is presented. Significant reduction of peak demands is shown quantitatively for all of the four regions. Based on these positive results, an elasticity based scheme that takes into account user discomfort is proposed for reducing monetary and environmental issues faced by today's utilities.

This thesis studies a single item periodic review inventory problem with stochastic demand, random price and quotation cost. It differs from the traditional inventory model in that at the beginning of each period, a decision is made whether to pay the quotation cost to get the price information. If it is decided to request a price quote then the next decision is on how many units to order; otherwise, there will be no order. An (r, S1, S2) policy with r < S2, S1 <= S2 is proposed for the problem with two prices. It prescribes that when the inventory is less than or equal to r, the price quotation is requested; if the higher price is quoted, then order up to S1, otherwise to S2. There are two cases, r < S1 or S1 <= r. In the first case, every time the price is quoted, an order is placed. It is a single reorder point two order-up-to levels policy that can be considered as an extension of the (s, S) policy. In the second case, S1 <= r, it is possible to “request a quote but not buy” if the quoted price is not favorable when the inventory is between S1 and r. Two total cost functions are derived for the cases r < S1 <= S2 and S1 <= r < S2 respectively. Then optimization algorithms are devised based on the properties of the cost functions and tested in numerical study. The algorithms successfully find the optimal policies in all of the 135 test cases. Compared to the exhaustive search, the running time of the optimization algorithm is reduced significantly. The numerical study shows that the optimal (r, S1, S2) policy can save up to 50% by ordering up to different levels for different prices, compared to the optimal (s, S) policy. It also reveals that in some cases it is optimal to search price speculatively, that is with S1 < r, to request a quote but only place an order when the lower price is realized, when the inventory level is between S1 and r.

El desarrollo y las avances recientes de la tecnología de los ordenadores y de la tecnología de alta velocidad de redes han hecho posible que las aplicaciones de video bajo demanda estén conectadas a "shared-computing" servidores reemplazando los sistemas tradicionales donde cada aplicación tenía su propia máquina dedicada para servirla. La aplicación de video bajo demanda permite a los usuarios seleccionar de una lista de videos su película favorita y ver su reproducción a su gusto.Sin embargo, la aplicación de video bajo demanda se considera como una de las aplicaciones que debería soportar largos "video streams", que consumen muchos recursos como el anch de banda de red y I/O, a gran número de clientes. Por eso, el servidor de video debería asegurar los recursos necesarios para cada "stream" durante un periodo de tiempo largo (e.g. 7200 segundos) para que los clientes reproduzcan el video sin "jitter" y "starvation" en sus búferes.Esta tesis presenta el diseño y la implementación de un Servidor Proxy de Video (VPS) que puede proveer video bajo demanda interactiva. El VPS consiste de tres componentes (partes) principales. La primera parte es el Modulo de Control de Admisión (ACM) que recibe las peticiones de los clientes, negocia los recursos requeridos, y decide si la petición puede ser aceptada o rechazada basado en la disponibilidad de los recursos. La segunda parte es el Modulo de Manejo de los Recursos (RMM) que maneja los recursos del sistema como el CPU, la Memoria, la Red, y el Disco. Este consta de cuatro "brokers" que reservan a los recursos necesarios basado en una política predefinida. La tercera parte es el algoritmo CB_MDA "Credit_Based Media Delivery Algorithm" que controla y regula el flujo de los "streams" del video. La CB_MDA utiliza una combinación de canales unicast y "multicast" para transmitir el video. Los "streams" de "multicast" se inician para empezar a emitir el video desde el principio, mientras los canales unicast se usan para juntar los llegados tardes a un "stream multicast" apropiado. En la implementación, el CB_MDA detecta los momentos cuando el servidor tiene disponibilidad de recursos y les asigna a los usuarios apropiados para crear un trabajo en adelanto. / The recent advances and development of inexpensive computers and high speed networking technology have enabled the Video on Demand (VoD) application to connect to shared-computing servers, replacing the traditional computing environments where each application was having its own dedicated special purpose computing hardware. The VoD application enables the viewer to select, from a list of video files, his favourite video file and watch its reproduction at will.However, the VoD application is known as one of the applications that must provide long-lived video streams which consume high resources such as I/O and network bandwidth to a large number of clients. Therefore, a video server must secure the necessary resources for each stream during a long period of time (e.g. 7200 seconds) so that the clients can reproduce (play) the video data without witnessing jitter or starvation in their buffers.This thesis presents the design and implementation for a video proxy server (VPS) which can provide interactive video on demand. The VPS consists of three main parts. The first part is the Admission Control Module which receives the clients' requests, negotiates the required resources, and decides whether to accept or reject a client based on the available resources. The second part is the Resources Management Module which manages several shared resources such as the CPU, the Memory, the Network and the Disk It consists of four brokers that can reserve the necessary resources based on a predefined policy. The third part is the CB_MDA algorithm which is responsible for regulating the resources assignment and scheduling the video streams. The CB_MDA uses a combination of multicast and unicast channels for transmitting the video data. The multicast streams are initiated to start a video file from the beginning while the unicast channels are used to join the later arrivals to the appropriate multicast stream. In the implementation, the CB_MDA discovers the period of time when the server has plenty of resources an assigns them to appropriate clients in order to create work-ahead video data.The thesis further goes beyond the design of the VPS and presents a video client architecture that can synchronize with the server and work as a plug-in for producing the video data on different players such as MPEG-Berkely player, Xine.etc.