This thesis presents a novel VLSI design of multi-code rate Low-Density Parity-Check code (LDPC) decoder for IEEE 802.16e standard. In order to support the different code rates adopted by the standard, this thesis proposes a programmable LDPC decoder architecture based on the edge-serial approach. This edge-serial architecture can perform the sequential check-node computation according to the internal sequence update commands. Any complex and irregular parity-check matrix can all be realized in the proposed architecture if the number of bit-nodes each check node connects does not exceed a certain bound. In addition to the high flexibility, this thesis also proposes several design optimization techniques suitable for the LDPC decoder. First, the designs of the LDPC decoders in the past all put more emphasis on the realization of check node function. This thesis instead applies a novel bit-node major approach which can lead to more compact design. Secondly, a fine-grain message update method is used which allows more rapid message passing such that the decoder can converge in less cycles. In addition, almost half of the message memory can be reduced. Furthermore, based on the bit-node major decoder design, the early termination scheme can be utilized to partially terminate the function of some bit nodes to reduce the decoding cycles. The other salient features also include the rescheduling of the message update order to allow the overlap of different decoding iterations in order to reduce effect of the possible message update hazard due to the long internal pipeline latency. Based on the proposed optimization methods, our experimental results show that the hardware cost can be reduced by 23.1% while the decoding cycles can be reduced by 27.4%. The proposed LDPC decoder architecture has been realized by using 0.18 µm technology with the total gate count of 316k. Our experimental shows that the proposed LDPC decoder can run up to 235 MHz and deliver the average of 116 Mbps throughput.

This thesis presents the results of an experimental study on single-charge effects in nanoscale Josephson junctions and Cooper pair transistors (CPTs). In nanoscale Josephson junctions the charging energy EC becomes significant at sub-Kelvin temperatures and single-charge effects, such as the Coulomb blockade of Cooper pair tunneling, influence the transport properties. In order to observe charging effects in a single Josephson junction, the impedance of the electromagnetic environment surrounding the junction has to be larger than the quantum resistance (RQ=h/4e2≈6.45kΩ). In this work the high impedance environment is obtained by biasing the sample under test (single Josephson junction or CPT) with four one-dimensional Josephson junction arrays having SQUID geometry. The advantage of this configuration is the possibility of tuning in situ the effective impedance of the electromagnetic environment. By applying a magnetic field perpendicular to the SQUID loops, the Josephson energy EJ of the SQUIDs is suppressed, resulting in an increase of the measured zero bias resistance of the arrays of several orders of magnitude (104< R0 (Ω) <109). This bias method enables the measurement of the same sample in environments with different impedance. As the impedance of the environment is increased, the current-voltage characteristics (IVCs) of the single Josephson junction and of the CPT show a well defined Coulomb blockade feature with a region of negative differential resistance, signature of the coherent tunneling of single Cooper pairs. The measured IVCs of a single Josephson junction with SQUID geometry in the high impedance environment show a qualitative agreement with the Bloch band theory as the EJ/EC ratio of the junction is tuned with the magnetic field. We also studied a single nontunable Josephson junction with strong coupling (EJ/EC > 1), where the exact dual of the overdamped Josephson effect is realized, resulting in a dual shape of the IVC, where the roles of current and voltage are exchanged. Here, we make for the first time a detailed quantitative comparison with a theory which includes the effect of fluctuations due to the finite temperature of the environment. The measurements on CPTs in the high impedance environment showed that the Coulomb blockade voltage is modulated periodically by the gate-induced charge. The gate-voltage dependence of the CPT changes from e-periodic to 2e-periodic as the impedance of the environment is increased. The high impedance environment reduces quasiparticle tunneling rates, thereby restoring the even parity of the CPT island. This behavior suggests that high impedance leads can be used to effectively suppress quasiparticle poisoning. / QC 20100928

Optioner är ett instrument som investerare kan använda för att spekulera i framtida upp-eller nedgångar på olika tillgångar. Om dessa optioner är felprissatta finns det möjlighet att göra riskfria vinster med hjälp av Stolls köp-säljparitet. Tidigare studier visar att marknaden inte alltid är effektiv i sin prissättning av aktieindexoptioner och att det därigenom finns möjlighet till arbitrage. Denna studie undersöker huruvida marknaden är effektiv i sin prissättning av VINX30 aktieindexoptioner, d.v.s. finns det möjlighet till arbitrag på VINX30 aktieindexoptioner? / Options are an instrument which investors can use to speculate in future pricemovements on different assets. If these options are misspriced there are an opportunity to get riskfree profit by using Stolls put-call parity. Earlier research shows that the market sometimes is inefficient when pricing stock index options allowing arbitrage. This study investigate whether the market is efficient in the pricing of VINX30 stock index options, i.e. are there arbitrage opportunities on VINX30 stock index options?

This paper considers the situation of Congolese women and their almost complete social, political and economic marginalization in society. The Congolese constitution formulates the principle of gender parity between men and women; however, numerous provisions of the law still actively discriminate against women, relegating them to the status of second-class citizens. The violent conflict that the Congo has experienced and continues to experience has only exacerbated the socio-economic and cultural differences in status between men and women. How are Congolese women responding to these obstacles and have they been able to make any sustainable gains in doing so? The findings of this paper contend that despite the inequities that they experience in the social, political and economic spheres, Congolese women have in fact been able to take steps towards achieving gender equality. The conflict that has so negatively affected them has also provided them with intended and unintended opportunities for improving their situation. One such opportunity is evident in the creation of City of Joy, a women empowerment program established and developed entirely by Congolese women. A refuge for survivors of sexual violence, City of Joy helps rehabilitate these women with the hope that they will have acquired the necessary tools to catalyze social change as they are reintegrated into their respective communities after the six-month program. City of Joy as a case study illustrates both the opportunities for empowerment and change as well as the difficulties of providing women with meaningful agency given the structural obstacles that they are faced with. Although it is difficult to evaluate the long-term success and sustainability of the program, the general observations that can be gleaned from this example demonstrate that war and conflict can create fresh beginnings and new opportunities for women to produce their own social, political and economic realities. City of Joy, although limited in scope, is a socially enhancing program and a pragmatic step toward increasing the probability of a peaceful outcome in the aftermath of a brutal and long-lasting conflict and will ultimately have a positive long-term effect Congolese society.

The Qweak experiment at Thomas Jefferson National Accelerator Facility (Jefferson Lab) will measure the proton's weak charge by measuring the parity violating asymmetry in elastic electron-proton scattering at very low momentum transfer, with the aim of determining the proton's weak charge with 4% combined statistical and systematic errors. The experimental apparatus includes a longitudinally polarized electron beam, a liquid hydrogen target, a room temperature toroidal magnetic spectrometer, and a set of precision detectors for the scattered electrons. The toroidal magnetic spectrometer, which will deflect away the inelastic scattered electrons and focus the elastic scattered electrons onto the detectors, plays a crucially important role in the experiment. In this thesis, in order to meet the requirements for the installation and calibration of the toroidal magnetic spectrometer, the numerical simulation of the spectrometer's magnetic field based on a realistic magnet model is discussed, a precise 3D field mapping is introduced, and some simulation results are provided. The zero-crossing analysis technique, which can be used to precisely infer the individual coil locations of the toroidal magnet, is presented and explored in detail. / October 2007

As one of the most powerful error-correcting codes, Low-density parity check codes are widely used in digital communications. Because of the performance of LDPC codes are capable to close the shannon limited extraordinarily, LDPC codes are to be used in the new Digital Video Broadcast-Satellite-Second Generation(DVB-S2) and it is the first time that LDPC codes are included in the broadcast standard in 2003. In this thesis, a restructured parity-check matrices which can be divided into sub-matrices for LDPC code in DVB-S2 is provided. Corresponded to this restructured parity-check matrix, a reconstructed decoding table is invented. The encoding table of DVB-S2 standard only could obtain the unknown check nodes from known variable nodes, while the decoding table this thesis provided could obtain the unknown variable nodes from known check nodes what is exactly the Layered-massage passing algorithm needed. Layered-message passing algorithm which also known as "Turbo-decoding message passing" is used to reduce the decoding iterations and memory storage for messages. The thesis also investigate Bp algorithm, lambda-min algorithm, Min-sum algorithm and SISO-s algorithm, meanwhile, simulation results of these algorithms and schedules are also presented.

This paper aims to explain the current account imbalances between the United States of America, Japan and China. According to theory, such imbalances should offset each other so that the international balance of payments account is zero. The study also tests the Uncovered Interest Rate Parity (UIP) theory for the same sample of countries. The focus is on the empirics of the topic, therefore time-series analysis is used. The results suggest that American current account deficit can indeed be explained by the surpluses of the Japanese and Chinese current accounts. Furthermore, the conclusion regarding the UIP is that it simply does not hold in the real world. Finally, the main implication of this study is that the Asian countries will eventually buy up American assets if the trend of imbalances continues.

In this thesis, we extend applications of Low-Density Parity-Check (LDPC) codes to a combination of constituent sub-channels, which is a mixture of Gaussian channels with erasures. This model, for example, represents a common channel in magnetic recordings where thermal asperities in the system are detected and represented at the decoder as erasures. Although this channel is practically useful, we cannot find any previous work that evaluates performance of LDPC codes over this channel. We are also interested in practical issues such as designing robust LDPC codes for the mixture channel and predicting performance variations due to erasure patterns (random and burst), and finite block lengths. On time varying channels, a common error control strategy is to adapt the coding rate according to available channel state information (CSI). An effective way to realize this coding strategy is to use a single code and puncture it in a rate-compatible fashion, a so-called rate-compatible punctured code (RCPC). We are interested in the existence of good puncturing patterns for rate-changes that minimize performance loss. We show the existence of good puncturing patterns with analysis and verify the results with simulations. Universality of a channel code across a broad range of coding rates is a theoretically interesting topic. We are interested in the possibility of using the puncturing technique proposed in this thesis for designing universal LDPC codes. We also consider how to design high rate LDPC codes by puncturing low rate LDPC codes. The new design method can take advantage of longer effect block lengths, sparser parity-check matrices, and larger minimum distances of low rate LDPC codes.

A circuit design of Low Density Parity Check (LDPC) decoder for IEEE 802.16e systems is with new overlapped method is proposed in this thesis. This circuit can be operated with 19 modes which are corresponding to block sizes of 576, ¡K, 2304. LDPC decoders can be implemented by using iterations with Variable Node and Check Node Processes. The hardware utilization ratio, which can be enhanced from 50% to 100% by using our proposed overlapped method, is better than traditional overlapped method. In [2], the traditional overlapped method utilization ratio just can be enhanced from 50% to 75% for IEEE 802.16e LDPC decoder with code rate 1/2. Under the same operating frequency, our proposed method can further increase 25% when compared with traditional overlapped method [2]. In this thesis, we also propose two circuit architectures to increase the operating frequency. First, we use a faster comparison circuit in our comparison unit [1]. Second, we use Carry Save Adder¡]CSA¡^method [8] to replace the common adder unit. The circuit is carried out by TSMC CMOS 0.18£gm 1P6M process with chip area 3.11 x 3.08 mm2. In the gate level simulation, the output data rate of this circuit is above 78.4MHz, so the circuit can meet the requirement of IEEE 802.16e system.

This dissertation includes two chapters in the field of international finances about foreign exchange rate predictability and testing purchase power parity. In each chapter, we build the theory, methodology, and the empirical results to present the paper¡¦s construction. The first chapter, we studies whether the pure price inflation rate which is extracted from stock return can help us to test the relative of purchasing power parity in where Asian countries include Malaysia, Korea, Taiwan, Thailand, Hong Kong, and Singapore against the United States. The paper of Chowdhry et al. (2005) argue that relative PPP may not hold for the official price inflation rates which is constructed from consumer price indices, since relative price changes and other frictions cause price to be sticky. Thus, they use the Fisher equation and Fama-French three factors elaborately to build up a model on the nominal return of real risk-free asset to extract the pure price inflation rates. Their argument is supported in the case of Japan, Germany, the United States, and the United Kingdom. We are interested in the case of some Asian countries. So, this chapter, we extend the model and methodology of Chowdhry et al. (2005) to test the relative PPP for Asian countries. If our empirical evidence is firmly supported, it will be a strongly reconfirmed the elaborated idea of Chowdhry et al. (2005). In our study, the PPP rule is not supported for Asian countries since joint null hypothesis of a=0 and b=1 are rejected at all horizons except Taiwan at monthly horizon. The testing results by constrained seeming unrelated regression (SUR) and system equation in pooled data are similar to the tests of country-by-country. Therefore, we apply the methods of panel unite root from Im et al. (2003), Maddala and Wu (1999), and Pesaran (2007) to test the PPP doctrine, and it is strongly supported PPP for Asian countries. The second chapter, we extract the estimated data of pure price inflation by Chowdhry et al. (2005), and use the data to build up a nonlinear STR (smooth transition autoregressive) model by Granger and Teräsvirta (1993), then compare the performance of linear or nonlinear model of exchange rate predictability with random walk model in the United States, the United Kingdom, Japan, and Germany. This study has presented evidences that the extracted inflation rates offer a good predictability on the prediction of exchange rate for the United Kingdom and Germany. Those extracted data in which are calculated from the industry portfolio returns of stock market. The issue of series correlation in regression error does matter the estimated coefficients £]k, thus we estimate the simulation of Gaussian bootstrap distribution for testing variables with Newey West standard deviation in regression estimate. The empirical evidences show that the PPP doctrine affects the predictability performance of exchange rate change by the extracted inflation rates.