scholarly journals Digital Closed-Loop Driving Technique Using the PFD-Based CORDIC Algorithm for a Biaxial Resonant Microaccelerometer

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Bo Yang ◽  
Lei Wu ◽  
Binlong Wang ◽  
Qiuhua Wang
Keyword(s):  
System Performance ◽  
Closed Loop ◽  
Sampling Frequency ◽  
Cordic Algorithm ◽  
Conventional System ◽  
Oscillation System ◽  
Performance Improvements ◽  
Bias Stability ◽  
Coordinate Rotation ◽  
Frequency Detector

A digital closed-loop driving technique is presented in this paper that uses the PFD- (phase frequency detector-) based CORDIC (coordinate rotation digital computer) algorithm for a biaxial resonant microaccelerometer. A conventional digital closed-loop self-oscillation system based on the CORDIC algorithm is implemented and simulated using Simulink software to verify the system performance. The system performance simulations reveal that the incompatibility between the sampling frequency and effective bits of AD and DA convertors limits further performance improvements. Therefore, digital, closed-loop self-oscillation using the PFD-based CORDIC algorithm is designed to further optimize the system performance. The system experimental results illustrate that the optimized system using the PFD-based CORDIC improves the bias stability of the resonant microaccelerometer by more than 5.320 times compared to the conventional system. This demonstrates that the optimized digital closed-loop driving technique using the PFD-based CORDIC for the biaxial resonant microaccelerometer is effective.

scholarly journals Complex relationship between seasonal streamflow forecast skill and value in reservoir operations

2017 ◽  
Vol 21 (9) ◽  
pp. 4841-4859 ◽  
Author(s):  
Sean W. D. Turner ◽  
James C. Bennett ◽  
David E. Robertson ◽  
Stefano Galelli
Keyword(s):  
System Performance ◽  
Research Effort ◽  
Forecast Accuracy ◽  
Strong Relationship ◽  
Forecast Skill ◽  
Severe Drought ◽  
Forecast Performance ◽  
Performance Improvements ◽  
Sensitivity Assessment ◽  
Seasonal Streamflow

Abstract. Considerable research effort has recently been directed at improving and operationalising ensemble seasonal streamflow forecasts. Whilst this creates new opportunities for improving the performance of water resources systems, there may also be associated risks. Here, we explore these potential risks by examining the sensitivity of forecast value (improvement in system performance brought about by adopting forecasts) to changes in the forecast skill for a range of hypothetical reservoir designs with contrasting operating objectives. Forecast-informed operations are simulated using rolling horizon, adaptive control and then benchmarked against optimised control rules to assess performance improvements. Results show that there exists a strong relationship between forecast skill and value for systems operated to maintain a target water level. But this relationship breaks down when the reservoir is operated to satisfy a target demand for water; good forecast accuracy does not necessarily translate into performance improvement. We show that the primary cause of this behaviour is the buffering role played by storage in water supply reservoirs, which renders the forecast superfluous for long periods of the operation. System performance depends primarily on forecast accuracy when critical decisions are made – namely during severe drought. As it is not possible to know in advance if a forecast will perform well at such moments, we advocate measuring the consistency of forecast performance, through bootstrap resampling, to indicate potential usefulness in storage operations. Our results highlight the need for sensitivity assessment in value-of-forecast studies involving reservoirs with supply objectives.

The Performance of Air-Air Ejectors With Triangular Tabbed Driving Nozzles

2006 ◽  
Author(s):  
S. F. McBean ◽  
A. M. Birk
Keyword(s):  
Experimental Investigation ◽  
System Performance ◽  
Experimental Testing ◽  
Back Pressure ◽  
Tube Diameter ◽  
Performance Parameters ◽  
Mixing Performance ◽  
Performance Improvements ◽  
Significant Performance ◽  
Ejector System

This paper describes an experimental investigation into the effects of geometrical variations on ejector system performance when the driving nozzle includes delta mixing tabs. Mixing tabs have been shown to provide good mixing performance with comparable back-pressure penalties to other types of enhanced mixing nozzles. The performance parameters of most interest are pumping, mixing, and back-pressure. Geometric parameters studied include standoff distance, mixing-tube diameter, and tab angle. Experimental testing showed significant performance improvements in mixing and pumping with a decrease in tab angle. Maximum mixing was found to occur with tab angles positioned at 120°. Exceptional mixing was also observed with increased standoff. Back-pressure was shown to increase with increasing standoff and decreasing tab angle, but was not affected by mixing-tube diameter. In addition, a zone of recirculation was identified at the entrance to the mixing-tube. This zone is thought to have an influence on ejector performance.

Intelligent Tracking and Positioning of Targets Using Passive Sensing Systems

2019 ◽  
pp. 286-305
Author(s):  
Saad Iqbal ◽  
Usman Iqbal ◽  
Syed Ali Hassan
Keyword(s):  
Machine Learning ◽  
Signal Processing ◽  
System Performance ◽  
Target Localization ◽  
The Other ◽  
Conventional System ◽  
Sensing Systems ◽  
Passive Sensing ◽  
Indoor Scenarios ◽  
Localization And Tracking

Target localization and tracking has always been a hot topic in all eras of communication studies. Conventional system used radars for the purpose of locating and/or tracking an object using the classical methods of signal processing. Radars are generally classified as active and passive, where the former uses both transmitter and receivers simultaneously to perform the localization task. On the other hand, passive radars use existing illuminators of opportunity such as wi-fi or GSM signals to perform the aforementioned tasks. Although they perform detection using classical correlation methods and CFAR, recently machine learning has been used in various application of passive sensing to elevate the system performance. The latest developed models for intelligent RF passive sensing system for both outdoor and indoor scenarios are discussed in this chapter, which will give insight to the readers about their designing.

Design and flight testing of closed-loop simple adaptive control for a biplane micro air vehicle

2019 ◽  
Vol 234 (6) ◽  
pp. 677-689
Author(s):  
Shuvrangshu Jana ◽  
Mayur Shewale ◽  
Susheel Balasubramaniam ◽  
Harikumar Kandath ◽  
M Seetharama Bhat
Keyword(s):  
Adaptive Control ◽  
System Dynamics ◽  
System Performance ◽  
Closed Loop ◽  
Flight Test ◽  
Adaptive Controller ◽  
Micro Air Vehicle ◽  
Plant Performance ◽  
Superior Performance ◽  
Air Vehicle

This article presents the implementation of closed-loop simple adaptive control on fixed-wing micro air vehicle dynamics to improve flight performance characteristics. It is known that to retain the micro air vehicle system performance during the entire flight regime is difficult due to model uncertainties, large parameter variation and wind disturbances compared to flight velocity. An adaptive controller can adapt to the uncertainties but the complexity involved in their implementation is high due to unavailability of required sensor information and computational resources on a micro air vehicle platform. Lack of flight test results in the open literature incorporating adaptive control so far can be partially attributed to this complexity. In this case, adaptive control architecture is implemented in such a way that only the uncertainties in the system dynamics are taken care of by the adaptive control and desired nominal plant performance is achieved by the basic controller. The proposed adaptive controller architecture is implemented in real flight test, and improvement of tracking performance over a proportional–integral–derivative controller is demonstrated which illustrates superior performance to conventional architectures. The proposed design approach can be implemented easily to an existing system, and system performance can be enhanced in the presence of unmodelled and uncertain system dynamics.

Containerization Method for Logistic Cost Reduction Based on Closed-Loop Supply Chain Model

2015 ◽  
Author(s):  
Xinyan Ou ◽  
Qing Chang ◽  
Guoxian Xiao ◽  
Jorge Arinez
Keyword(s):  
Mathematical Model ◽  
Supply Chain ◽  
System Performance ◽  
Closed Loop ◽  
Cost Savings ◽  
Supply Chain System ◽  
Logistics Cost ◽  
Closed Loop Supply Chain ◽  
Chain System ◽  
Logistic Cost

Logistics cost is an important contributor to the overall cost in a supply chain system. By using collapsible containers, the frequency of return freight can be reduced and the return of containers can be optimized, leading to potential logistic cost savings. However, the dynamic behavior of container flows due to demand, inventory, storage, and repair requirements make it difficult to accurately analyze container system performance. An accurate estimation of this collapsible container usage impact is of great importance for decision-making. This paper describes the development of a mathematical model of the container dynamic flow system by using the collapsible containers. A continuous time, discrete space Markov process is used for stochastic scenario. The model determines the total cost savings, based on the collapsible rate, the number of collapsible containers, the performance of the factory and the supplier and the transportation environment. The presented mathematical formulation enables the evaluation of the system performance. A case study of collapsible container supply chain system demonstrates the advantages of this methodology. In addition, a simulation model of this stochastic system is presented to verify the mathematical model. Simulation tests are conducted to demonstrate the potential logistics cost savings in the closed-loop supply chain system.

Thermal Performance in Multi-Pass Solar Systems With Well-Mixed Storage

1987 ◽  
Vol 109 (2) ◽  
pp. 94-100
Author(s):  
J. M. Gordon ◽  
Y. Zarmi
Keyword(s):  
System Performance ◽  
Closed Loop ◽  
Open Loop ◽  
Thermal Coupling ◽  
Storage Tanks ◽  
Actual System ◽  
Solar Systems ◽  
Penalty Factor ◽  
First Time ◽  
Partial Depletion

An approximate analysis of multi-pass, closed-loop solar systems with well-mixed storage tanks is presented. The thermal coupling of the storage tank both to the collector-storage loop (“charging” cycle) and the load-storage loop (“discharging” cycle) is shown to reduce system performance by a penalty factor, called the partial depletion factor, when compared to one-pass, open-loop systems in which the storage fluid is completely consumed by the load by the end of each 24-hour day (total depletion). This penalty factor is typically around 20 percent for systems with a daytime-only load and 30 percent for systems with a nighttime-only load. Our analysis provides, for the first time, the explanation for the findings of various experiments and numerical simulations. We establish the approximate validity of a “quasi-steady state” approach, wherein actual system performance is approximated by a calculation based on the repetition of one representative day. The approach is general in that it is applicable to all solar collector types.

An Improved High-Accuracy CORDIC Algorithm for DSC in Endoscopic Ultrasonography System

2011 ◽  
Vol 130-134 ◽  
pp. 37-40
Author(s):  
Yan Li ◽  
Yun Xia Hao ◽  
Ming Li ◽  
Yi Wang ◽  
Xiao Dong Chen ◽  
...  
Keyword(s):  
Endoscopic Ultrasonography ◽  
Near Field ◽  
Optimization Methods ◽  
High Accuracy ◽  
Cordic Algorithm ◽  
Logic Element ◽  
Imaging Experiment ◽  
Coordinate Rotation ◽  
Coordinate Conversion ◽  
Scan Conversion

An Improved High-Accuracy CORDIC (COordinate Rotation Digital Computer) algorithm for digital scan conversion is presented in this paper to enhance the accuracy and speed of coordinate conversion for Endoscopic Ultrasonography. Several optimization methods are carried out to make coordinate conversion implemented more exactly with fewer resources of FPGA. In the paper, the Cartesian coordinates are re-demarcated to save LE (Logic Element) resources of FPGA. The bit width of data, the scale factor correction and the convergence range are all optimized to improve the accuracy of the algorithm. Further more, a special processing for the near-field data is carried out to reduce the errors of digital scan conversion. With a full pipeline structure implemented on FPGA, the Improved High-Accuracy CORDIC algorithm is validated by both simulation and real-time ultrasound imaging experiment, making the accuracy enhanced and the image quality improved.

Digital Controller Design for Sense Mode of Micro-Machined Gyroscope

2013 ◽  
Vol 336-338 ◽  
pp. 940-943
Author(s):  
Long Wang ◽  
Chun Hua He ◽  
Yu Xian Liu ◽  
Da Chuan Liu ◽  
Long Tao Lin ◽  
...  
Keyword(s):  
Closed Loop ◽  
Force Feedback ◽  
Sine Wave ◽  
Measurement Range ◽  
Open Loop ◽  
Loop System ◽  
Cordic Algorithm ◽  
Sense Mode ◽  
Wave Source ◽  
Loop Control

This paper presents one kind of digital closed loop control system of MEMS (Micro Electro-Mechanical Systems) vibratory gyroscope, particularly concentrating on the sense mode of MEMS gyroscope. The controller consists of a sine wave source realized by CORDIC algorithm, multiplication demodulators, some low-pass filters and force feedback rebalance module. Compared with the open loop sense system of gyroscope, the closed loop sense system has larger measurement range and wider bandwidth. Besides, the sine wave source realized with CORDIC algorithm can save hardware resources. The digital system is demonstrated on a PCB with a FPGA on it. The test results show that the measurement range of the closed loop system can be increased to 3 times by the open loop, and the bandwidth can be extended to 262Hz from 27Hz of the open loop system.

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