481 research outputs found
Effect of cooking time on physical properties of almond milk-based lemak cili api gravy
One of the crucial elements in developing or reformulating product is to maintain the quality throughout its entire shelf life. This study aims to determine the effect of different cooking time on the almond milk-based of lemak cili api gravy. Various cooking times of 5, 10, 15, 20, 25 and 30 minutes were employed to the almond milk-based lemak cili api gravy followed by determination of their effects on physical properties such as total soluble solids content, pH and colour. pH was determined by using a pH meter. Refractometer was used to evaluate the total soluble solids content of almond milk-based lemak cili api gravy. The colours were determined by using spectrophotometer which expressed as L*, a* and b* values. Results showed that almond milk-based lemak cili api gravy has constant values of total soluble solids with pH range of 5 to 6, which can be classified as low acid food. Colour analysis showed that the lightness (L*) and yellowness (b*) are significantly increased while redness (a*) decreased. In conclusion, this study shows that physical properties of almond milk-based lemak cili api gravy changes by increasing the cooking time
Sampling from a system-theoretic viewpoint: Part II - Noncausal solutions
This paper puts to use concepts and tools introduced in Part I to address a wide spectrum of noncausal sampling and reconstruction problems. Particularly, we follow the system-theoretic paradigm by using systems as signal generators to account for available information and system norms (L2 and L∞) as performance measures. The proposed optimization-based approach recovers many known solutions, derived hitherto by different methods, as special cases under different assumptions about acquisition or reconstructing devices (e.g., polynomial and exponential cardinal splines for fixed samplers and the Sampling Theorem and its modifications in the case when both sampler and interpolator are design parameters). We also derive new results, such as versions of the Sampling Theorem for downsampling and reconstruction from noisy measurements, the continuous-time invariance of a wide class of optimal sampling-and-reconstruction circuits, etcetera
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Channel equalization to achieve high bit rates in discrete multitone systems
textMulticarrier modulation (MCM) techniques such as orthogonal frequency division
multiplexing (OFDM) and discrete multi-tone (DMT) modulation are attractive
for high-speed data communications due to the ease with which MCM can combat
channel dispersion. With all the benefits MCM could give, DMT modulation has an
extra ability to perform dynamic bit loading, which has the potential to exploit fully
the available bandwidth in a slowly time-varying channel. In broadband wireline
communications, DMT modulation is standardized for asymmetric digital subscribe
line (ADSL) and very-high-bit-rate digital subscriber line (VDSL) modems. ADSL
and VDSL standards are used by telephone companies to provide high speed data
service to residences and offices.
In an ADSL receiver, an equalizer is required to compensate for the channel’s
dispersion in the time domain and the channel’s distortion in the frequency domain
of the transmitted waveform. This dissertation proposes design methods for linear
equalizers to increase the bit rate of the connection. The methods are amenable
to implementation on programmable fixed-point digital signal processors, which are
employed in ADSL/VDSL transceivers.
A conventional ADSL equalizer consists of a time-domain equalizer, a fast
Fourier transform, and a frequency domain equalizer. The time domain equalizer
(TEQ) is a finite impulse response filter that when coupled with a discretized channel
produces an equivalent channel whose impulse response is shorter than that of
the discretized channel. This channel shortening is required by the ADSL standards.
In this dissertation, I first propose a linear phase TEQ design that exploits symmetry
in existing eigen-filter approaches such as minimum mean square error(MMSE),
maximum shortening signal to noise ratio (MSSNR) and minimum intersymbol interference
(Min-ISI) equalizers. TEQs with symmetric coefficients can reach the
same performance as non-symmetric ones with much lower training complexity.
Second, I improve Min-ISI design. I reformulate the cost function to make
long TEQs design feasible. I remove the dependency of transmission delay in order
to reduce the complexity associated with delay optimization. The quantized
weighting is introduced to further lower the complexity. I also propose an iterative
optimization procedure of Min-ISI that completely avoids Cholesky decomposition
hence is better suited for a fixed-point implementation.
Finally I propose a dual-path TEQ structure, which designs a standard singleFIR
TEQ to achieve good bit rate over the entire transmission bandwidth, and
designs another FIR TEQ to improve the bit rate over a subset of subcarriers. Dualpath
TEQ can be viewed as a special case of a complex valued filter bank structure
that delivers the best bit rate of existing DMT equalizers. However, dual-path
TEQ provides a very good tradeoff between achievable bit rate vs. implementation
complexity on a programmable digital signal processor.Electrical and Computer Engineerin
An investigation into glottal waveform based speech coding
Coding of voiced speech by extraction of the glottal waveform has shown promise in improving the efficiency of speech coding systems. This thesis describes an investigation into the performance of such a system.
The effect of reverberation on the radiation impedance at the lips is shown to be negligible under normal conditions. Also, the accuracy of the Image Method for adding artificial reverberation to anechoic speech recordings is established.
A new algorithm, Pre-emphasised Maximum Likelihood Epoch Detection (PMLED), for Glottal Closure Instant detection is proposed. The algorithm is tested on natural speech and is shown to be both accurate and robust.
Two techniques for giottai waveform estimation, Closed Phase Inverse Filtering (CPIF) and Iterative Adaptive Inverse Filtering (IAIF), are compared. In tandem with an LF model fitting procedure, both techniques display a high degree of accuracy However, IAIF is found to be slightly more robust.
Based on these results, a Glottal Excited Linear Predictive (GELP) coding system for voiced speech is proposed and tested. Using a differential LF parameter quantisation scheme, the system achieves speech quality similar to that of U S Federal Standard 1016 CELP at a lower mean bit rate while incurring no extra delay
Reports on industrial information technology. Vol. 12
The 12th volume of Reports on Industrial Information Technology presents some selected results of research achieved at the Institute of Industrial Information Technology during the last two years.These results have contributed to many cooperative projects with partners from academia and industry and cover current research interests including signal and image processing, pattern recognition, distributed systems, powerline communications, automotive applications, and robotics
Guidance, Navigation and Control System of a Hopper Spacecraft Simulator
The space hopper simulator project drew its origin from a partnership with Penn State University to compete in the Google Lunar XPRIZE competition. Lehigh University is tasked with the exploring the guidance, navigation and control (GN&C) system of the hopper spacecraft. To simulate the dynamics and flight behavior of the concept, Earth-based multirotor flying platforms were developed with the end goal of executing the hopping maneuver.The overall project has been ongoing for more than 5 years and went through several major revisions to fix flaws discovered in the previous design. As older students graduate and new teams are form, knowledge and experience are lost in the process. Due to the time it take to relearn and redesign the simulators, the project progress only get as far as achieving radio controlled flight. The current and 3rd generation development team aims to change that by developing both the hardware and software using modular design.With modular design, the manufacturing, repair and modification process for the multirotor speed up significantly. The damaged component can be replaced with little effort. In addition to the hardware advantages, the software modules enable concurrent development of both a PID and a Fuzzy Logic based flight control system using similar avionics and software architecture. Since the flight operating system function by linking the various software modules, individual modules can easily be swapped to test different control laws, electronic devices, etc. The software modules are also capable of being reused in other applications, such as running the thrust test stand and logging data with the wireless ground station.In theory and simulation, the GN&C system is quite simple. The hopping guidance trajectory can be generated by a set of linear and trigonometric equations. The trajectory can be optimized by minimizing the total energy consumption at the end of the hopping maneuver. The navigational data can be collected from the GPS and localized for the cascade PID controllers to achieve the desired trajectory. In the ideal world, everything is simple and easy.In the real world, a range of problems arise during implementation. Factors such as time delay and noises significantly impact the performance of the control system, making stable aggressive tuning very difficult to achieve. In an attempt to improve the condition, a number of digital filters such as the moving average filter and the Kalman filter were explored. In addition, every sub-system was analyzed in depth to optimize for speed. This resulted in 3 major revisions in changing flight computer and programming languages.Even though the main topic of this research is the guidance, navigation and control system, the project quickly expanded into a systems engineering problem. Everything must work well together in order for the aircraft to achieve stable flight
Sampling from a system-theoretic viewpoint
This paper studies a system-theoretic approach to the problem of reconstructing an analog signal from its samples. The idea, borrowed from earlier treatments in the control literature, is to address the problem as a hybrid model-matching problem in which performance is measured by system norms. \ud
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The paper is split into three parts. In Part I we present the paradigm and revise the lifting technique, which is our main technical tool. In Part II optimal samplers and holds are designed for various analog signal reconstruction problems. In some cases one component is fixed while the remaining are designed, in other cases all three components are designed simultaneously. No causality requirements are imposed in Part II, which allows to use frequency domain arguments, in particular the lifted frequency response as introduced in Part I. In Part III the main emphasis is placed on a systematic incorporation of causality constraints into the optimal design of reconstructors. We consider reconstruction problems, in which the sampling (acquisition) device is given and the performance is measured by the -norm of the reconstruction error. The problem is solved under the constraint that the optimal reconstructor is -causal for a given i.e., that its impulse response is zero in the time interval where is the sampling period. We derive a closed-form state-space solution of the problem, which is based on the spectral factorization of a rational transfer function
Reflectance-Based Pulse Oximetry for the Chest and Wrist
Reflectance-based pulse oximetry is a technique used for noninvasively monitoring the oxygen saturation (SpO2) and pulse rate (PR). However, there is little supporting evidence that it can accurately collect measurements from the chest and wrist. In this project, a reflectance-based pulse oximeter was built and used to collect measurements while sitting, standing, during self-induced hypoxia, and during self-induced hyperventilation then compared to the measurements taken by a HOMEDIC Deluxe Pulse Oximeter. The prototype was able to accurately measure within an error of + 1% and ±3% for SpO2 and PR respectively from the wrist while an error of ±1% and +4% for SpO2 and PR respectively from the chest
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