408 research outputs found
Complexity Reduction in the CORDIC Algorithm by using MUXes
Nowadays, the CORDIC algorithm plays an important role to deal with the non-linear functions in hardware. In this thesis, a novel methodology is described to reduce the complexity in an unrolled CORDIC architecture, which gives higher speed, lesser area, and lower power consumption. That is, MUXes are used to replace adder stages. Five different unrolled CORDIC architectures have been implemented in ASIC using a 65nm CMOS technology with Low Power High V_T transistors. The area, computational speed, accuracy, error behavior, and power consumption have been analyzed. The design aim is to reduce the power consumption, which is more and more important depending on the area. As a result the area and power consumption get 7.9% lower and 27.2% lower separately, and the speed is 22.9% higher compared to the original unrolled CORDIC architecture
Game among Interdependent Networks: The Impact of Rationality on System Robustness
Many real-world systems are composed of interdependent networks that rely on
one another. Such networks are typically designed and operated by different
entities, who aim at maximizing their own payoffs. There exists a game among
these entities when designing their own networks. In this paper, we study the
game investigating how the rational behaviors of entities impact the system
robustness. We first introduce a mathematical model to quantify the interacting
payoffs among varying entities. Then we study the Nash equilibrium of the game
and compare it with the optimal social welfare. We reveal that the cooperation
among different entities can be reached to maximize the social welfare in
continuous game only when the average degree of each network is constant.
Therefore, the huge gap between Nash equilibrium and optimal social welfare
generally exists. The rationality of entities makes the system inherently
deficient and even renders it extremely vulnerable in some cases. We analyze
our model for two concrete systems with continuous strategy space and discrete
strategy space, respectively. Furthermore, we uncover some factors (such as
weakening coupled strength of interdependent networks, designing suitable
topology dependency of the system) that help reduce the gap and the system
vulnerability
Study on Mooring Design and Calculation Method of Ocean Farm Based on Time-Domain Potential Flow Theory
In order to calculate the mooring force of a new semi-submerged Ocean Farm quickly and accurately, based on the unsteady time-domain potential flow theory and combined the catenary model, the control equation of mooring cable is established, and the mooring force of the platform under the wave spectrum is calculated. First of all, based on the actual situation of the ocean environment and platform, the mooring design of the platform is carried out, and the failure analysis and sensitivity analysis of the single anchor chain by the time domain coupling method are adopted: including different water depth, cycle, pretension size, anchor chain layout direction and wind speed, etc. The analysis results confirm the reliability of anchoring method. Based on this, the mooring point location of the platform is determined, the force of each anchor chain in the anchoring process is calculated, and the mooring force and the number of mooring cables are obtained for each cable that satisfies the specification, the results of this paper can provide theoretical calculation methods for mooring setting and mooring force calculation of similar offshore platforms
Development of a Highly Flexible and Stretchable Tubular Shape Tactile Sensor Array
University of Minnesota M.S.E.E. thesis. August 2016. Major: Electrical Engineering. Advisors: Jing Bai, Debao Zhou. 1 computer file (PDF); viii, 68 pages.Highly flexible skin-like sensors, such as electrical skin (e-skin) sensor for pressure measurement, have the potential to provide quantitative physical contact assessments, when equipped on household and medical devices to benefit human society. One of the promising applications is to monitor the contact pressure of a colonoscope to the colonic wall during a colonoscopy to reduce the possibility of perforation and hemorrhaging.Colon, as the largest intestine, is a long winding tube at end of human's digestive tract. Many disorders affect the colon's ability to work properly, thus the American Cancer Society suggests that citizens over 50 years old should be subject to a colon screen test. However, risks do exist during colonoscopy. A rate of 0.19% perforation occurs in the diagnostic colonoscopy. Many attempts have been made to fabricate highly stretchable electronic devices, but no effort has been made to design or investigate the mechanical behaviors of a tubular-shaped e-skin that meet the need for controlling the risks during colonoscopy. In this project, a high performance three-layer tactile sensor array was designed and fabricated, and a pressure detection system was set up as well. The operating mode was thoroughly investigated and the pressure detection on curved surface, such as a tube was realized. A detailed study about false positive error was performed to improve the sensor’s reliability and accuracy. Based on a tubular-shaped, highly flexible skin-like sensor array we developed, we conducted both modeling and experimental studies on the change of the maximum pressure distribution of a tubular e-skin sensor under various bending conditions with and without external compressive forces. These studies revealed the value of the maximum stress on a tubular shaped e-skin sensor array when bent. The measuring errors due to bending in pressure detection during colonoscopy can be quantified for compensation. Thus, high accuracy diagnose can be achieved. Based on all these work, the pressure detection in the colon-simulator was successfully realized. The results could also be used to address strategies on optimizing the design of tactile sensors for other medical application
RESEARCH ON THE MOTION RESPONSE OF AQUACULTURE SHIP AND TANK SLOSHING UNDER ROLLING RESONANCE
The double-row and double-chamfered aquaculture tank is a special tank structure of the aquaculture ship. The tank sloshing of this structure is coupled with the hull motion, which has an important impact on the safety of the hull motion. In the present study, research on the tank sloshing and hull motion response of aquaculture ships was conducted based on the model seakeeping and tank sloshing tests in regular waves. The test results were compared with the numerical simulation results of solid loading without sloshing. The results showed that the numerical simulation of the pitch motion was consistent with the amplitude-frequency response curve of the experimental results. Under certain transverse wave conditions, a large discrepancy existed between the amplitude-frequency response curve of the heave motion by the numerical simulation and the test results, and the roll motion differed most from the experimental result. Severe roll resonance occurred when the wave length-ship length ratio was 0.6. The roll motion amplitude was increased by 183.2%. Therefore, compared with aquaculture ships without sloshing, the sloshing of the tank has little effect on the pitch but has a great impact on the roll and heave motions, with the most significant effect on the roll motion
Ergodic Achievable Rate Analysis and Optimization of RIS-assisted Millimeter-Wave MIMO Communication Systems
Reconfigurable intelligent surfaces (RISs) have emerged as a prospective
technology for next-generation wireless networks due to their potential in
coverage and capacity enhancement. Previous works on achievable rate analysis
of RIS-assisted communication systems have mainly focused on the
rich-scattering environment where Rayleigh and Rician channel models can be
applied. This work studies the ergodic achievable rate of RIS-assisted
multiple-input multiple-output communication systems in millimeter-wave band
with limited scattering under the Saleh-Valenzuela channel model. Firstly, we
derive an upper bound of the ergodic achievable rate by means of majorization
theory and Jensen's inequality. The upper bound shows that the ergodic
achievable rate increases logarithmically with the number of antennas at the
base station (BS) and user, the number of the reflection units at the RIS, and
the eigenvalues of the steering matrices associated with the BS, user and RIS.
Then, we aim to maximize the ergodic achievable rate by jointly optimizing the
transmit covariance matrix at the BS and the reflection coefficients at the
RIS. Specifically, the transmit covariance matrix is optimized by the
water-filling algorithm and the reflection coefficients are optimized using the
Riemannian conjugate gradient algorithm. Simulation results validate the
effectiveness of the proposed optimization algorithms.Comment: 30 pages, 11 figure
DriveSceneGen: Generating Diverse and Realistic Driving Scenarios from Scratch
Realistic and diverse traffic scenarios in large quantities are crucial for
the development and validation of autonomous driving systems. However, owing to
numerous difficulties in the data collection process and the reliance on
intensive annotations, real-world datasets lack sufficient quantity and
diversity to support the increasing demand for data. This work introduces
DriveSceneGen, a data-driven driving scenario generation method that learns
from the real-world driving dataset and generates entire dynamic driving
scenarios from scratch. DriveSceneGen is able to generate novel driving
scenarios that align with real-world data distributions with high fidelity and
diversity. Experimental results on 5k generated scenarios highlight the
generation quality, diversity, and scalability compared to real-world datasets.
To the best of our knowledge, DriveSceneGen is the first method that generates
novel driving scenarios involving both static map elements and dynamic traffic
participants from scratch.Comment: 7 pages, 5 figures, 2 table
CARLA-Loc: Synthetic SLAM Dataset with Full-stack Sensor Setup in Challenging Weather and Dynamic Environments
The robustness of SLAM algorithms in challenging environmental conditions is
crucial for autonomous driving, but the impact of these conditions are unknown
while given the difficulty of arbitrarily changing the relevant environmental
parameters of the same environment in the real world. Therefore, we propose
CARLA-Loc, a synthetic dataset of challenging and dynamic environments built on
CARLA simulator. We integrate multiple sensors into the dataset with strict
calibration, synchronization and precise timestamping. 7 maps and 42 sequences
are posed in our dataset with different dynamic levels and weather conditions.
Objects in both stereo images and point clouds are well-segmented with their
class labels. We evaluate 5 visual-based and 4 LiDAR-based approaches on varies
sequences and analyze the effect of challenging environmental factors on the
localization accuracy, showing the applicability of proposed dataset for
validating SLAM algorithms
Effect of Volume Loading Rate and C/N on Ship Domestic Sewage Treatment by Two Membrane Bioreactors
Design of ship sewage treatment systems that not only satisfy the use of small space on board but also meets International Maritime Organisation (IMO) latest emission standards is still a challenging problem for ship industry. This study provides a comparative disquisition between two different MBR reactors i.e, air-lift multilevel circulation membrane reactor (AMCMBR) and anaerobic/anoxic/aerobic membrane reactor (AOA-MBR) for domestic sewage treatment. The influence of pollutants volume loading rate (VLR) and C/N on effluent chemical oxygen demand (COD), ammonium nitrogen (NH4+-N) and TN for marine domestic sewage was analyzed. The results revealed that AMCMBR showed better removal efficiencies for COD and TN than AOA-MBR. The volume of AMCMBR was only half of the AOA-MBR. In addition, high average value of mixed liquor volatile suspended solids (MLVSS)/mixed liquid suspended solids (MLSS) (i.e. 0.75) of AMCMBR indicated high biomass and good pollutants removal achieved by this reactor. An interesting phenomenon was found in the study regarding Urease activity for the two reactors. Urease activity for AMCMBR in different working conditions all exceeded AOA-MBR and there exist no clear difference of NR activities between AMCMBR and AOA-MBR except for low C/N ratio (i.e. 6 and 4). This phenomenon proved that AMCMBR has a greater performance for treating ship domestic wastewater
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