scholarly journals Analysis of Instantaneous Feedback Queue with Heterogeneous Servers

Mathematics ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 2186
Author(s):  
Agassi Melikov ◽  
Sevinj Aliyeva ◽  
János Sztrik
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Threshold Value ◽  
High Accuracy ◽  
Approximate Algorithms ◽  
Heterogeneous Servers ◽  
Bernoulli Scheme ◽  
Markov Modulated ◽  
Steady State Probabilities ◽  
Feedback Queue

A system with heterogeneous servers, Markov Modulated Poisson flow and instantaneous feedback is studied. The primary call is serviced on a high-speed server, and after it is serviced, each call, according to the Bernoulli scheme, either leaves the system or requires re-servicing. After the completion of servicing of a call in a slow server, according to the Bernoulli scheme, it also either leaves the system or requires re-servicing. If upon arrival of a primary call the queue length of such calls exceeds a certain threshold value and the slow server is free, then the incoming primary call, according to the Bernoulli scheme, is either sent to the slow server or joins its own queue. A mathematical model of the studied system is constructed in the form of a three-dimensional Markov chain. Approximate algorithms for calculating the steady-state probabilities of the models with finite and infinite queues are proposed and their high accuracy is shown. The results of numerical experiments are presented.

Monte Carlo estimates of critical percolation probabilities

1967 ◽  
Vol 63 (2) ◽  
pp. 477-479 ◽  
Author(s):  
P. Dean ◽  
N. F. Bird
Keyword(s):  
Monte Carlo ◽  
Cluster Size ◽  
High Speed ◽  
Three Dimensional ◽  
High Accuracy ◽  
Size Distributions ◽  
Critical Percolation ◽  
Monte Carlo Studies ◽  
Very High ◽  
The Way

In this paper we present results for the critical percolation probabilities of a number of two- and three-dimensional lattices. These results are based upon Monte Carlo studies of the way in which cluster-size distributions vary as the number of occupied sites in a lattice is progressively increased; the principle of the method has been described in some detail in an earlier publication (Dean (1)) in which the results of studies carried out on the ACE computer were reported. The use of a KDF 9 computer with a 32K word high-speed store has now enabled us to obtain results of a very high accuracy indeed; in those cases where our values for critical probabilities can be checked against exactly known values, they differ by no more than 0·1%.

Error Analysis of the ATOS 3D Optical Scanner in Vehicle Measurement

2013 ◽  
Vol 365-366 ◽  
pp. 654-657
Author(s):  
Xue Dong Xie ◽  
Wei Ling Zhao
Keyword(s):  
Measurement System ◽  
Reference Point ◽  
High Speed ◽  
Three Dimensional ◽  
High Accuracy ◽  
Actual Measurement ◽  
Optical Scanning ◽  
Optical Scanner ◽  
Actual Use ◽  
Multiple Scan

ATOS three-dimensional optical scanner is one of the most advanced technologically three-dimensional optical scanning devices. It can automatically put together the multiple scan view image by the reference point of the measurement system, with high accuracy, high speed Etc. It is widely used in automobiles. The paper combines with the experience in vehicle measurements, analysis the error cause in the actual use, points out ways to reduce or eliminate error. It has the great application value to actual measurement.

Simulation study on the performance of time-over-threshold based positioning in monolithic PET detectors

2021 ◽  
Author(s):  
Charlotte Thyssen ◽  
Karel Deprez ◽  
Pieter Mollet ◽  
Roel Van Holen ◽  
Stefaan Vandenberghe
Keyword(s):  
High Speed ◽  
Threshold Value ◽  
High Accuracy ◽  
Nearest Neighbour ◽  
Pixel Size ◽  
Photodetector Array ◽  
Novel Approach ◽  
Pet Detectors ◽  
The Impact ◽  
Energy Determination

Abstract The vast majority of PET detectors in the field today is based on pixelated scintillators. Yet, the resolution of this type of detector is limited by the pixel size. To overcome this limitation one can use monolithic detectors. However, this detector architecture demands specific and high-speed detector readout of the photodetector array. A commonly used approach is to integrate the current pulses generated by every pixel but such circuitry quickly becomes bulky, power consuming and expensive. The objective of this work is to investigate a novel readout and event positioning scheme for monolithic PET detectors, based on Time-over-Threshold (ToT). In this case, we measure the time that the pulse is above a certain threshold through a comparator. The pulse widths are used for event positioning using a mean nearest neighbour approach (mNNToT). For energy determination one integrating multiplexed channel is foreseen. We evaluate the positioning accuracy and uniformity of such a ToT detector by means of Monte Carlo simulations. The impact of the threshold value is investigated and the results are compared to a detector using mean nearest neighbour with pulse-integration (mNNint), which has already proven to allow sub-mm resolution. We show minimal degradation in spatial resolution and bias performance compared to mNNint. The highest threshold results in the worst resolution performance but degradation remains below 0.1 mm. Bias is largely constant over different thresholds for mNNToT and close to identical to mNNint. Furthermore we show that Time-over-Threshold performs well in terms of detector uniformity and that scattered photons can be positioned inside the crystal with high accuracy. We conclude from this work that ToT is a valuable alternative to pulse-integration for monolithic PET detectors. This novel approach has an impact on PET detector development since it has the advantage of lower power consumption, compactness and inherent amplitude-to-time conversion.

scholarly journals Retrial Queues with Unreliable Servers and Delayed Feedback

Mathematics ◽  
2021 ◽  
Vol 9 (19) ◽  
pp. 2415
Author(s):  
Agassi Melikov ◽  
Sevinj Aliyeva ◽  
Janos Sztrik
Keyword(s):  
Steady State ◽  
Performance Measures ◽  
Numerical Experiments ◽  
Three Dimensional ◽  
Delayed Feedback ◽  
Retrial Queues ◽  
Bernoulli Feedback ◽  
Bernoulli Scheme ◽  
Multi Server ◽  
Steady State Probabilities

In this paper, models of unreliable multi-server retrial queues with delayed feedback are examined. The Bernoulli retrial is allowed upon the arrival of both primary (from outside) and feedback customers (from orbit), as well as the Bernoulli feedback that may occur after each service in this system. Servers can break down both during the service of customers and when they are idle. If a server breaks down during the service of a customer, then the interrupted customer, in accordance with the Bernoulli scheme, decides either to leave the system or join a common orbit of retrial and feedback customers. An approximate method, based on the space merging approach of three-dimensional Markov chains, is proposed for the calculation of the steady-state probabilities, as well as performance measures of the system. The results of the numerical experiments are demonstrated.

FULLY AUTOMATIC DIGITAL FRINGE PROJECTION MEASUREMENT FOR 3D FACIAL SURFACE

2019 ◽  
Vol 19 (02) ◽  
pp. 1940019
Author(s):  
CHENG-YANG LIU ◽  
CHENG-YU WANG ◽  
LI-WEI TENG
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Facial Feature ◽  
High Accuracy ◽  
Industrial Applications ◽  
Fringe Projection ◽  
Projection Technique ◽  
Digital Light Processing ◽  
Digital Fringe Projection ◽  
Fully Automatic

Digital fringe projection technique is widely used in industrial applications with high accuracy and measurement speed. In this study, a fully automatic high-speed digital fringe projection technique is presented to profile 3D facial characteristics. The structured light with fringe pattern is used to be the light source in the measurement system and is projected by a digital light processing projector. The distorted fringe patterns from facial surface are captured by the digital camera. The absolute phase maps are calculated by using phase-shifting and quality guided path unwrapping algorithm. A complete, 3D facial feature is obtained by our measurement. We achieved simultaneous phase acquisition, reconstruction and three-dimensional (3D) exhibition at a speed of 0.5[Formula: see text]s. This technique may provide a high accuracy and real-time 3D facial measurement for biometric verification.

scholarly journals Analysis of Queueing System MMPP/M/K/K with Delayed Feedback

Mathematics ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 1128 ◽  
Author(s):  
Agassi Melikov ◽  
Sevinj Aliyeva ◽  
Janos Sztrik
Keyword(s):  
Numerical Experiments ◽  
Queueing System ◽  
Three Dimensional ◽  
Delayed Feedback ◽  
State Dependent ◽  
Repeated Calls ◽  
Markov Modulated Poisson Process ◽  
Markov Modulated ◽  
Steady State Probabilities ◽  
Dependent Probability

The model of multi-channel queuing system with Markov modulated Poisson process (MMPP) flow and delayed feedback is considered. After the customer is served completely, they will decide either to join the retrial group again for another service (feedback) with some state-dependent probability or to leave the system forever with complimentary probability. Feedback calls organize an orbit of repeated calls (r-calls). If upon arrival of an r-call all the channels of the system are busy, then it either leaves the system with some state-dependent probability or with a complementary probability returns to orbit. Methods to calculate the steady-state probabilities of the appropriate three-dimensional Markov chain as well as performance measures of investigated system are developed. Results of numerical experiments are demonstrated.

High-speed brightfield 3-D imaging and 3-D image analysis of thick and overlapped cell clusters in cytological preparations

1994 ◽  
Vol 52 ◽  
pp. 218-219
Author(s):  
Robert W. Mackin
Keyword(s):  
Image Analysis ◽  
High Speed ◽  
Three Dimensional ◽  
Image Data ◽  
Ccd Camera ◽  
Objective Lens ◽  
Array Processor ◽  
Vaginal Smears ◽  
Low Contrast ◽  
Computer Controlled

This paper presents two advances towards the automated three-dimensional (3-D) analysis of thick and heavily-overlapped regions in cytological preparations such as cervical/vaginal smears. First, a high speed 3-D brightfield microscope has been developed, allowing the acquisition of image data at speeds approaching 30 optical slices per second. Second, algorithms have been developed to detect and segment nuclei in spite of the extremely high image variability and low contrast typical of such regions. The analysis of such regions is inherently a 3-D problem that cannot be solved reliably with conventional 2-D imaging and image analysis methods.High-Speed 3-D imaging of the specimen is accomplished by moving the specimen axially relative to the objective lens of a standard microscope (Zeiss) at a speed of 30 steps per second, where the stepsize is adjustable from 0.2 - 5μm. The specimen is mounted on a computer-controlled, piezoelectric microstage (Burleigh PZS-100, 68/μm displacement). At each step, an optical slice is acquired using a CCD camera (SONY XC-11/71 IP, Dalsa CA-D1-0256, and CA-D2-0512 have been used) connected to a 4-node array processor system based on the Intel i860 chip.

Effects of Three-Dimensional Pressure Gradients on High-Speed Turbulent Boundary Layers

2021 ◽  
Author(s):  
Scott J. Peltier ◽  
Brian E. Rice ◽  
Ethan Johnson ◽  
Venkateswaran Narayanaswamy ◽  
Marvin E. Sellers
Keyword(s):  
Boundary Layers ◽  
High Speed ◽  
Three Dimensional ◽  
Turbulent Boundary Layers ◽  
Pressure Gradients
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