IF-Sampling Digital Beamforming with Bit-Stream Processing.

Beamforming in receivers improves signal-to-noise ratio (SNR), and enables spatial filtering of incoming signals, which helps reject interferers. However, power consump-tion, area, and routing complexity needed with an increasing number of elements have been a bottleneck to implementing efficient beamforming systems. Especially, digital beamforming (DBF), despite its versatility, has not been attractive for low-cost on-chip implementation due to its high power consumption and large die area for multiple high-performance analog-to-digital converters (ADCs) and an intensive digital signal process-ing (DSP) unit. This thesis presents a new DBF receiver architecture with direct intermediate frequency (IF) sampling. By adopting IF sampling in DBF, a digital-intensive beamforming receiver, which provides highly flexible and accurate beamforming, is achieved. The IF-sampling DBF receiver architecture is efficiently implemented with continuous-time band-pass delta-sigma modulators (CTBPDSMs) and bit-stream processing (BSP). They have been separately investigated, and have not been considered for DBF until now. The unique combination of CTBPDSMs and BSP enables low-power and area-efficient DBF by removing the need for digital multipliers and multiple decimators. Two prototype digital beamformers (prototype I and prototype II) are fabricated in 65 nm complementary metal-oxide-semiconductor (CMOS) technology. The prototype I forms a single beam from four 265 MHz IF inputs, and an array signal-to-noise-plus-distortion ratio (SNDR) of 56.6 dB is achieved over a 10 MHz bandwidth. The prototype I consumes 67.2 mW, and occupies 0.16 mm2. The prototype II forms two simultaneous beams from eight 260 MHz IF inputs, and an array SNDR of 63.3 dB is achieved over a 10 MHz bandwidth. The prototype II consumes 123.7 mW, and occupies 0.28 mm2. The two prototypes are the first on-chip implementation of IF-sampling DBF.PhDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/116778/1/jaehun_1.pd

A Sustainable Development Strategy for the Uzbekistan Textile Industry: The Results of a SWOT-AHP Analysis

Uzbekistan is paying great attention to the textile industry as an industry offering a traditional production advantage, coming to the conclusion that it is necessary to establish and implement effective policies. In Uzbekistan as in other developing countries, whereas there are many strategic directions and development strategies to be considered for key industries, investment resources are limited. Therefore, it is necessary to prioritize and to apply limited resources accordingly. Even though research on the textile industry in Uzbekistan is ongoing for a long time, most of the resultant literature concerns only general industrial trends and pertinent investment and advancement strategies. The present study examined sustainable, concrete, and effective development strategy directions for the Uzbekistan textile industry using strengths, weaknesses, opportunities, and threats (SWOT) analytic hierarchy process (AHP) model. The SWOT-AHP model was tested in a case study on Uzbekistan’s textile industry. In the case study, the results were presented in an illustrative way by utilizing the quantitative information achieved by the model. The results indicated that the weakness and opportunity (WO) strategy had the highest importance, and suggested accordingly that priority should be given to that strategy for Uzbekistan’s textile industry development. The results further suggested that the Uzbekistan government should endeavor to upgrade obsolescent technology and solve the problems of high-priced imported raw materials and workers’ low education level, which are weak points of the textile industry of that country. Also, Uzbekistan should gradually shift the industrial structure from raw cotton to finished textile exportation, which offers relatively high added economic value. To achieve this, the Uzbek government needs to promote joint ventures and strategic alliances with foreign companies wishing to enter the textile industry through foreign direct investment (FDI) schemes

Examining Roles of Tour Dure Producers for Social Capital and Innovativeness in Community-Based Tourism

The Dure community is a traditional meeting and collaborative effort for solving tasks and issues in rural farming villages in Korea. Recently, the South Korean government has tried to revitalize Dure communities to develop tourism businesses in local provinces. Tour Dure projects aimed at revitalizing local communities and promoting sustainable economic development have been operating since 2013. Tour Dure producers, as change agents, play a critical role in the Tour Dure projects. The purpose of this study is to reveal the producers’ roles in realizing community-based tourism (CBT). Using partial least squares structural equation modeling, this study analyzes the relationship between the producers’ role and social capital in local communities and the subsequent impact on residents’ innovativeness and life satisfaction. The results show that the producer’s role is important in creating social capital, improving innovativeness, and, as a result, residents’ life satisfaction. The present study suggests further implications for academics and policy makers focused on sustainable CBT

Implementation of a Prototype Positioning System for LBS on U-campus

Location-based service is one of the most popular buzzwords in the field of U-cities. Positioning a user is an essential ingredient of a location-based system in a U-city. For outdoor positioning, GPS based practical solutions have been introduced. However, the measurement error of GPS is too big for it to be used for U-campus services, because the size of a campus is smaller than that of a city. We propose the Relative-Interpolation Method to improve the accuracy of outdoor positioning. However, indoor positioning is also necessary for a U-campus because the GPS signal is not available inside buildings. For indoor positioning, various systems including Cricket, Active Badge, and so on have been introduced. These methods require special equipment dedicated to positioning. Our method does not require such equipment because it determines the user’s position based on the received signal strength indicators (RSSIs) from access points (AP) which are already installed for WLAN. The algorithm we use for indoor positioning is a kind of fingerprinting method. However, our algorithm builds a decision tree instead of a look-up table in the off-line phase. Therefore, the proposed method is faster than the existing indoor positioning methods in the real-time phase. We integrated our indoor and outdoor positioning methods and implemented a prototype indoor-outdoor positioning system on a laptop. The experimental results are discussed in this paper. In implementing the prototype, we also implemented a C# library function which can be used to read the RSSIs from the APs

Large-Area and Ultrathin MEMS Mirror Using Silicon Micro Rim

A large-area and ultrathin MEMS (microelectromechanical system) mirror can provide efficient light-coupling, a large scanning area, and high energy efficiency for actuation. However, the ultrathin mirror is significantly vulnerable to diverse film deformation due to residual thin film stresses, so that high flatness of the mirror is hardly achieved. Here, we report a MEMS mirror of large-area and ultrathin membrane with high flatness by using the silicon rim microstructure (SRM). The ultrathin MEMS mirror with SRM (SRM-mirror) consists of aluminum (Al) deposited silicon nitride membrane, bimorph actuator, and the SRM. The SRM is simply fabricated underneath the silicon nitride membrane, and thus effectively inhibits the tensile stress relaxation of the membrane. As a result, the membrane has high flatness of 10.6 m−1 film curvature at minimum without any deformation. The electrothermal actuation of the SRM-mirror shows large tilting angles from 15° to −45° depending on the applied DC voltage of 0~4 VDC, preserving high flatness of the tilting membrane. This stable and statically actuated SRM-mirror spurs diverse micro-optic applications such as optical sensing, beam alignment, or optical switching

Enhancement of Brillouin light scattering signal with anti-reflection layers on magnetic thin films

The significant enhancement of Brillouin light scattering (BLS) spectroscopy intensity in a ferromagnetic thin film with an additional dielectric anti-reflection layer is experimentally investigated. The anti-reflection layer thickness dependent BLS measurements on ferromagnetic layers are performed systematically. Consequently, we observe that BLS signals are dramatically enhanced by more than 450% at a specific dielectric layer thickness due to the pure optical effect. Because of the large signal enhancements, the errors of the spin wave resonance peak frequencies are noticeably reduced as well. Since many magnetic properties such as the saturation magnetization, the surface anisotropy, and the exchange stiffness constant are determined by the spin wave resonance frequencies from the BLS spectra, the additional anti-reflection layer can help to improve the reliability of BLS experiments. Especially, the BLS signal improvement plays a crucial role in the precise determination of the interfacial Dzyaloshinskii-Moriya interaction (iDMI) energy density, since the iDMI energy density is calculated from the difference of Stokes and anti-Stokes resonance frequencies, which is typically order of 1 GHz. © 20201