Shading devices are frequently used to control solar gain through windows. Solar optical properties are very important in the energy analysis of windows. Transmittance, absorptance and reflectance are required to quantify solar heat gain through complex fenestration systems, which consist of combinations of glazing and shading layers. In this research the solar transmittance of a sheer blind was measured using a Broad Area Illuminating Integrating Sphere (BAI-IS). More specifically, the spectral directional-hemispherical transmittance was measured in the wavelength range of 0.4 µm to 2.0 µm. A “sheer blind” consists of soft fabric vanes, similar to a venetian blind, suspended between two vertical layers of sheer fabric. This arrangement is popular because it is attractive and it has potential application for daylighting. The vertical sheer fabric reduces the solar intensity and diffuses incident radiation; generally reducing solar gain and producing soft, natural illumination. The fabric vanes control the amount of light entering the room. Shading devices such as venetian blinds, sheer blinds and drapes have spatially non-uniform and light scattering surfaces. Hence, measurement error occurs if the solar optical properties are measured by traditional narrow-beam measurement techniques typically used in commercial spectrophotometers. To reduce this error, a BAI-IS is recommended. The BAI-IS apparatus consists of a 20-inch diameter integrating sphere, sample mounting system, monochromator, radiant source, lock-in-amplifier, photo sensor, optical chopper and various auxiliary devices. In order to improve reliability of the measurement the BAI-IS has recently been upgraded by replacing most of the key control and measurement equipment. The refurbishment of the BAI-IS apparatus was successful. The directionalhemispherical transmittance of a sheer blind from BAI-IS measurement was found to agree well with an analytical model.

In an anonymous credential system, when a credential has been shown for verification, none can identify the owner of the credential and link the relationship between any two credentials. The unlinkability is the crucial feature for any anonymous credential system. In 2002, Jan Camenisch and Anna Lysyanskaya proposed a signature scheme (CL signature) which allows users to demonstrate their credentials without revealing their identity information. However, CL signature is compounded of a lot of zero-knowledge proof technologies which cause inefficiency for CL signatures. Such heavy computation requirements may limit the scope which CL signatures can be applied to. In this thesis, we propose a new blind signature scheme based on ElGamal signatures and design an anonymous verification procedure which is more efficient than the CL signature scheme. Finally, we also implement our proposed protocols.

In this thesis, the blind phase estimator algorithms are studied, including Histogram Algorithm (HA), Modified Histogram Algorithm (MHA), Maximum Likelihood (ML), 4th power-law and modified 4th power-law to compare their performance under quadrature amplitude modulation and additive white gaussian noise(AWGN) channel. Owing to the development of wireless communication, I used the fading channel of wireless communication and studied the performance of all algorithms again. After differential encoding and quadrature amplitude modulation, signals enter additive white gaussian noise(AWGN), constant phase offset and fading channel. At receiver, I use the above estimator to find the phase offset. If there is not line of sight under fading channel, all estimators performance are not good from simulation results, if there is a strong line of sight, all estimators performance are good and approximate to the AWGN channel.

The analysis of this thesis concerns various problems associated with adaptive CDMA multi-user detection in asynchronous multi-path channels. Starting with some simple concept of Wiener filtering and correlating detector, we construct a novel adaptive decorrelating transversal filter suitable for CDMA multi-user detection in uplink channels. Then, we make use of the LMS and RLS algorithms to replace the traditional decorrelating transversal filter (which is also called inverse matrix based decorrelating detector) to make the scheme work fully adaptively. In this way, a great advantage in terms of computation load reduction is made possible. To further improve the detection efficiency, we will also make use of RAKE receiver to enhance the overall decision reliability in the proposed adaptive CDMA MUD scheme. Although the focus of this thesis is put on analysis, we will also use computer simulations to counter-check the results obtained from theoretical analysis, showing a very good match between the two. In the last part of the thesis, we will also discuss the various issues on fully blind implementation of the proposed adaptive CDMA MUD scheme with some useful multipath channel delay and amplitude estimation algorithms.

Digital signature is widely used to implement many secure protocols. A digital signature has three parameters. They are the message, the key pair, and the signature. In general, the message is given. The key pair is chosen randomly by the signer. The signature is computed from the message and the key pair. But in some cases, we can choose the value of one of the parameters, this may make it possible to other applications such as blind signatures or subliminal channels. There are some researches to discuss the relations between the parameters and the applications of the digital signatures. In this research, we will propose three new schemes as examples of this technique. The first one is a fair blind signature scheme. The other two are subliminal channel schemes. These three new schemes have some important properties. The concept of this research may help the future researches to find new applications of the digital signature. Meanwhile, these new schemes can show that how the concept can help us to develop or improve applications.

In this thesis, we propose a modified blind adaptive approach to MAI cancellation for synchronous DS-CDMA systems, termed PCMA Approach. It has the same advantage as MOE and CMA of suppressing MAI without the explicit knowledge of interference parameters. We study the effect of arrival and departure of new users to the synchronous blind multiuser receivers, namely MOE and CMA. The perturbation caused by this sudden birth or death of interferers is examined from the viewpoint of the change of the cost function under the noiseless assumption. It is shown that in the vicinity of lock convergence, the changes in the CMA and MOE costs are the same if the perturbation is small enough. But it is also observed that the transient behavior of the CMA detector becomes significantly less robust as the existing number of users approaches the processing gain. To overcome this question of the CMA detector, we employ a projection matrix P that can remove the desired signal from the received signal with other interferers unchanged. Finally its performance has been demonstrated by numerical results in comparison with CMOE, ANMMSE, BAMMSE and Linear MMSE. The proposed receiver can combat MAI, approach the performance of Linear MMSE and have a higher capacity and fast convergence rate for a time-varying user population.

In mobile radio systems, the bandwidth of spread spectrum signals for CDMA system is very wide. If the bandwidth exceeds the coherence bandwidth of the channel, the signal is transmitted in the frequency-selective channel, and the signal is severely distorted by the multiple propagation paths. Each bandwidth of the signals for Multi-Carrier CDMA system is smaller. If the bandwidth is smaller than the coherence bandwidth of the channel, the channel is said to be frequency-nonselective. Besides, the data rate of Multi-carrier-CDMA is higher than the data rate of CDMA. If the traditional combing detector is used for Multi-Carrier CDMA system, the channel coefficients have to be estimated first. The error of the estimated channel coefficients will result in the performance of detector degrade. The blind adaptive algorithm doesn

With the launch of networked handheld devices which can capture, store, compress, send and display a variety of audiovisual stimuli; high definition television (HDTV); streaming Internet protocol TV (IPTV) and websites such as Youtube, Facebook and Flickr etc., an enormous amount of visual data of visual data is making its way to consumers. Because of this, considerable time and resources are being expanded to ensure that the end user is presented with with a satisfactory quality of experience (QoE). While traditional QoE methods have focused on optimizing delivery networks with respect to throughput, buffer-lengths and capacity, perceptually optimized delivery of multimedia services is also fast gaining importance. This is especially timely given the explosive growth in (especially wireless) video traffic and expected shortfalls in bandwidth. These perceptual approaches attempt to deliver an optimized QoE to the end-user by utilizing objective measures of visual quality. In this thesis, we shall cover a variety of such algorithms that predict overall QoE of an image or a video, depending on the amount of information available for the algorithm design. Typically, quality assessment (QA) algorithms are classiffied on the basis of the amount of information that is available to the algorithm. This thesis will primarily focus on blind QA algorithms, where blind or no-reference (NR) QA refers to automatic quality assessment of an image/video using an algorithm which only utilizes the distorted image/video whose quality is being assessed. NR QA approaches are further classiffied on the basis of whether the algorithm had access to subjective/human opinion prior to deployment. Algorithms which use machine learning techniques along with human judgements of quality during the 'training' phase may be labelled 'opinion aware' algorithms. The first part of the thesis deals with such approaches. While such opinion aware-NR algorithms demonstrate good correlation with human perception on controlled databases, it is impossible to anticipate all of the different distortions that may occur in a practical system and hence train on them. In such cases, it is of interest to design QA algorithms that are not limited in their performance by training data. Approaches which operate without the knowledge of human judgements during the training phase are labelled as 'opinion unaware' (OU) algorithms. We propose such an approach in the second part of the thesis. Further, we propose new VQA algorithms in the last part of the dissertation to address the completely blind VQA problem. The proposed approach quantify disturbances introduced due to distortions and thereby predict the quality of distorted content even without any external knowledge about the pristine natural sources and hence zero shot models. / text

Federal and state vocational rehabilitation (VR) agencies are putting increased emphasis on, and providing more resources for, self-employment for individuals who are blind or visually-impaired since the Rehabilitation Act was amended in 1998. Additional emphasis is being placed on self-employment because VR system consumers – especially those who are blind or visually-impaired – are disproportionately likely to have difficulty obtaining other kinds of competitive employment in the aftermath of the 2007-2009 recession. The purpose of this quantitative study is to identify variables in the administrative records of the federal Rehabilitation Service Agency that impact self-employment outcomes and earnings among blind or visually-impaired consumers. The file, comprised of 13,998 cases closed in Texas from Fiscal Years 2008 through 2012, spans the national recession and subsequent slow recovery. From the original file, 798 cases closed through self-employment were examined by employment status at application, cost of services and returns on investments (ROI). This study found those who were self-employed at application were 50 times more likely to be self-employed at closure. Those who received assessments, diagnosis and treatment, technical assistance, and rehabilitation services were more likely to be self-employed at closure. The variables most closely related to weekly earnings at closure for self-employed consumers were: gender (male), being self-employed at application and receiving some form of rehabilitation technology. Disproportionate numbers of those who were self-employed at application were 55 to 65 and self-identified as White only with weekly earnings at application above the mean for the entire population of consumers whose cases were closed through self-employment. They received the fewest services on average over the shortest period of time at the lost average cost. Returns on investments in serving those who were self-employed at application were positive but small. The average cost of services provided to those employed at application was the highest. However, on average, they experienced decreases in the hours worked per week and weekly earnings. Thus, returns on investments were, on average, negative. Limitations of the study, implications for practice, and future research are discussed. / text

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