FPGA-Based Low-Power Speech Recognition with Recurrent Neural Networks

In this paper, a neural network based real-time speech recognition (SR) system is developed using an FPGA for very low-power operation. The implemented system employs two recurrent neural networks (RNNs); one is a speech-to-character RNN for acoustic modeling (AM) and the other is for character-level language modeling (LM). The system also employs a statistical word-level LM to improve the recognition accuracy. The results of the AM, the character-level LM, and the word-level LM are combined using a fairly simple N-best search algorithm instead of the hidden Markov model (HMM) based network. The RNNs are implemented using massively parallel processing elements (PEs) for low latency and high throughput. The weights are quantized to 6 bits to store all of them in the on-chip memory of an FPGA. The proposed algorithm is implemented on a Xilinx XC7Z045, and the system can operate much faster than real-time.Comment: Accepted to SiPS 201

Physicochemical Properties of Frozen Fish Muscle as Affected by Trimethylamine-N-oxide demethylase (TMAOase)

Gadoid fish, like Alaska pollock and Pacific whiting, have a high level of trimethylamine-N-oxide demethylase (TMAOase) that catalyzes the breakdown of trimethylamine-N-oxide (TMAO) to formaldehyde (FA) and dimethylamine (DMA) even during frozen storage. FA reacts with amino acid residues to promote covalent cross-links in the formation of inter- and intramolecular linkages between protein chains via covalent methylene bridges, resulting in textural toughening when frozen storage extends. Heading and gutting (H&G) or filleting, which are a common practice for seafood processing, often affects fish quality during refrigerated and/or frozen storage due to freeze- and FA-induced protein denaturation followed by aggregation. The primary goal of the study presented in the dissertation was to investigate physicochemical and textural properties of frozen Alaska pollock and Pacific whiting fillets as affected by postharvest processing and storage conditions, and further to measure the relationship between TMAOase activity and protein aggregation. In the first part (Chapter 3), TMAOase activity, FA content and physicochemical properties of frozen Pacific whiting fillet during frozen storage (-18 and -80°C) were investigated. Whole fish and H&G fish were stored under refrigeration for 0, 2, and 5 days and subsequently filleted and frozen. Frozen fillets were analyzed during 24 weeks of storage. TMAOase activity and FA content, which affect the textural quality of frozen fillet, were measured. FA induced by TMAOase increased at all treatments at -18°C as frozen storage extended to 24 weeks, but it was near zero at -80°C up to 12 weeks of storage. This study showed that textural quality and freshness were significantly lower when fillets were prepared from H&G fish than whole fish and stored at -18oC. Based on the finding from the first part, the second part (Chapters 4 and 5) evaluated various TMAOase-related (TMAOase activity, FA, DMA, and TMAO contents), physicochemical and textural properties of frozen Alaska pollock subjected to different freezing/thawing (F/T) cycles (0-12). TMAOase, FA and DMA contents significantly increased in fillets prepared from H&G fish as F/T cycles repeated. Interestingly, FA contents in fillets and drip were significantly reduced at 12-F/T, indicating that FA was possibly used for protein denaturation and textural toughness. F/T, which is often used to mimic long-term frozen storage, likely induced the rapid FA production by accumulated TMAOase in fish muscle as ice crystal formation was maximized. The last part of the study (Chapters 6 and 7) was to investigate the effect of various sodium phosphates [sodium tripolyphosphate (STPP)/tetrasodium pyrophosphate (TSPP) mixture, STPP, TSPP, trisodium pyrophosphate, sodium hexametaphosphate, and disodium phosphate anhydrous] on TMAOase- and freeze-induced protein denaturation followed by aggregation using 2 step approach (lab and pilot scale). For the lab-scale approach, using natural actomyosin (NAM) extracted from fresh Pacific whiting, the phosphate treatments were evaluated at various concentrations (0.1, 0.3, and 0.5%), with and without cryoprotectants (CP), at various (0, 3, and 9) freeze/thaw (F/T) cycles. The NAM mixture containing 0.5% STPP/TSPP, STPP, and TSPP along with CP exhibited low TMAOase activity, low FA production, high salt-soluble proteins (SSP) concentration, and high turbidity. Among the phosphate treatments, STPP appeared to be the most effective compound in retarding both FA- and freeze-induced protein denaturation and aggregation. NAM without CP were more rapidly denatured and aggregated than NAM treated with CP as F/T was repeated, resulting in a rapid increase in the degree of aggregation (DA). The DA, which was calculated using photographical image analysis, was correlated well with biochemical properties. For the application of phosphates in Alaska pollock surimi and fillet, both phosphate-injected fillets and phosphate-added surimi along with cryoprotectant (5% sugar and 4% sorbitol) were subjected to 0, 3, and 9 F/T cycles. The concentration of sodium phosphate retained in fillet was adjusted to 0.3% using poking (6 times), soaking (10 min), and draining (2 min). The effect of various sodium phosphates on physicochemical properties of fillet and surimi was different during repeated F/T. The differences observed might be attributed by the functionality of the various phosphates used including their chelation ability, pH, and protein interaction. As STPP and TSPP were more effective to control TMAOase activity of fillet and surimi than other phosphates, FA content, SSP extractability, drip/cook loss, and texture properties were also better controlled. In summary, even though H&G treatment before refrigeration has been commonly used to prevent cross contamination of microbes and TMAOase within fish flesh, this research concluded H&G treatment was not a necessary or favorable processing step for Pacific whiting and Alaska pollock. For the best quality, Pacific whiting whole fish should be stored at refrigerator for 2 days or less prior to filleting if stored at -18°C for 12 weeks, and Alaska pollock whole fish should be filleted and frozen within 3 days postharvest if fillets are to be stored frozen for longer periods. Quality reductions of fish muscle proteins by freeze- and FA-induced denaturation could be effectively retarded by the addition of STPP and/or TSPP as they inhibit TMAOase activity and reduce ice crystallization

Rotary Compressor Noise Analysis Using Mechanisms and Electromagnetics Coupled Approach

This research is conducted to investigate noise source and design low noise compressors. For improving energy efficiency, the rotary compressor with variable speed brushless DC motor is increasingly adopted for appliances. However brushless DC motor makes more compressor vibration than constant speed motor compressor at high speed operating condition. Therefore it is necessary to reduce noise and vibration for improving air conditioner quality. In this study, compressor’s noise and vibration are simulated using structural and electromagnetics coupled methods. To simulate the actual motor movements, precession motion of rotor is applied for simulatio

Generation of a Wide-Band Response Using Early-Time and Middle-Frequency Data Throught the Use of Orthogonal Fuctions

Abstract|Generation of a wide-band response using partial information from the time domain (TD) data and frequency domain (FD) data has been accomplished in this paper through the use of three different orthogonal functions, such as the continuous Laguerre functions, the Bessel-Chebyshev functions, and the associate Hermite functions. In this hybrid approach, one can generate the early-time response using the method of marching-on-in-time (MOT) and use the method of moment (MOM) to generate the middle-frequency response, as the low-frequency data may be unstable. Since the early-time and the middle-frequency data are mutually complimentary, they can provide the missing low- and high-frequency response and the late- time response, respectively. Even though obtaining middle-frequency response from an object needs more computation time than the low- frequency response, this approach has better performance for the interpolation and extrapolation of a wide-band response

Self-assembled nanocomplex between polymerized phenylboronic acid and doxorubicin for efficient tumor-targeted chemotherapy

Since the discovery that nano-scaled particulates can easily be incorporated into tumors via the enhanced permeability and retention (EPR) effect, such nanostructures have been exploited as therapeutic small molecule delivery systems. However, the convoluted synthetic process of conventional nanostructures has impeded their feasibility and reproducibility in clinical applications. Herein, we report an easily prepared formulation of self-assembled nanostructures for systemic delivery of the anti-cancer drug doxorubicin (DOX). Phenylboronic acid (PBA) was grafted onto the polymeric backbone of poly(maleic anhydride). pPBA-DOX nanocomplexes were prepared by simple mixing, on the basis of the strong interaction between the 1,3-diol of DOX and the PBA moiety on pPBA. Three nanocomplexes (1, 2, 4) were designed on the basis of [PBA]:[DOX] molar ratios of 1: 1, 2: 1, and 4: 1, respectively, to investigate the function of the residual PBA moiety as a targeting ligand. An acid-labile drug release profile was observed, owing to the intrinsic properties of the phenylboronic ester. Moreover, the tumor-targeting ability of the nanocomplexes was demonstrated, both in vitro by confocal microscopy and in vivo by fluorescence imaging, to be driven by an inherent property of the residual PBA. Ligand competition assays with free PBA pre-treatment demonstrated the targeting effect of the residual PBA from the nanocomplexes 2 and 4. Finally, the nanocomplexes 2 and 4, compared with the free DOX, exhibited significantly greater anti-cancer effects in vitro and even in vivo. Our pPBA-DOX nanocomplex enables a new paradigm for self-assembled nanostructures with potential biomedical applications.115Ysciescopu