maximum frequency
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2022 ◽  
Vol 15 (2) ◽  
pp. 1-31
Author(s):  
Joel Mandebi Mbongue ◽  
Danielle Tchuinkou Kwadjo ◽  
Alex Shuping ◽  
Christophe Bobda

Cloud deployments now increasingly exploit Field-Programmable Gate Array (FPGA) accelerators as part of virtual instances. While cloud FPGAs are still essentially single-tenant, the growing demand for efficient hardware acceleration paves the way to FPGA multi-tenancy. It then becomes necessary to explore architectures, design flows, and resource management features that aim at exposing multi-tenant FPGAs to the cloud users. In this article, we discuss a hardware/software architecture that supports provisioning space-shared FPGAs in Kernel-based Virtual Machine (KVM) clouds. The proposed hardware/software architecture introduces an FPGA organization that improves hardware consolidation and support hardware elasticity with minimal data movement overhead. It also relies on VirtIO to decrease communication latency between hardware and software domains. Prototyping the proposed architecture with a Virtex UltraScale+ FPGA demonstrated near specification maximum frequency for on-chip data movement and high throughput in virtual instance access to hardware accelerators. We demonstrate similar performance compared to single-tenant deployment while increasing FPGA utilization, which is one of the goals of virtualization. Overall, our FPGA design achieved about 2× higher maximum frequency than the state of the art and a bandwidth reaching up to 28 Gbps on 32-bit data width.


2022 ◽  
Vol 30 (1) ◽  
pp. 581-603
Author(s):  
Shamsiah Suhaili ◽  
Norhuzaimin Julai

Security has grown in importance as a study issue in recent years. Several cryptographic algorithms have been created to increase the performance of these information-protecting methods. One of the cryptography categories is a hash function. This paper proposes the implementation of the SHA-256 (Secure Hash Algorithm-256) hash function. The unfolding transformation approach was presented in this study to enhance the throughput of the SHA-256 design. The unfolding method is employed in the hash function by producing the hash value output based on modifying the SHA-256 structure. In this unfolding method, SHA-256 decreases the number of clock cycles required for traditional architecture by a factor of two, from 64 to 34 because of the delay. To put it another way, one cycle of the SHA-256 design can generate up to four parallel inputs for the output. As a result, the throughput of the SHA-256 design can be improved by reducing the number of cycles by 16 cycles. ModelSim was used to validate the output simulations created in Verilog code. The SHA-256 hash function factor four hardware implementation was successfully tested using the Altera DE2-115 FPGA board. According to timing simulation findings, the suggested unfolding hash function with factor four provides the most significant throughput of around 4196.30 Mbps. In contrast, the suggested unfolding with factor two surpassed the classic SHA-256 design in terms of maximum frequency. As a result, the throughput of SHA-256 increases 13.7% compared to unfolding factor two and 58.1% improvement from the conventional design of SHA-256 design.


2021 ◽  
Vol 50 (3) ◽  
pp. 25-27
Author(s):  
N. I. Volkov ◽  
Zh. V. Bespalova ◽  
P. A. Bazanov ◽  
I. V. Volosenok

With the aim of comparative examination of efficacy of different drugs and methods of endoscopic surgery in treatment of infertile women with genital endometriosis 548 patients were examined. Distinct advantages of combined treatment were revealed: surgical destruction of endometrial foci at the first stage and administration of antigonadotrophic preparations at the second stage. Maximum frequency of impregnation after such therapy was observed during first 6-8 months. By 11-12 months the index decreased to its minimum. So, it is reasonable to give up passive supervision after 12 months


Author(s):  
Baocai Wang ◽  
Huadong Sun ◽  
Wenfeng Li ◽  
Chao Yang ◽  
Wei Wei ◽  
...  

Author(s):  
Alireza Jamali

After proposing a natural metric for the space in which particles spin which implements the principle of maximum frequency, E=hf is generalised and its inverse Fourier transform is calculated. As a necessary result, a metric is found for the space in which quantum particles spin, hence the possibility of explanation of correlation of spacelike-separated particles is opened up.


Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 8132
Author(s):  
Jun Wang ◽  
Yien Xu ◽  
Xiaoxin Wu ◽  
Jiejie Huang ◽  
Xinsong Zhang ◽  
...  

An inertial response emulated control strategy of doubly-fed induction generators (DFIGs) is able to arrest their frequency decline following a severe frequency event. Nevertheless, the control coefficient is unchanged, so as to limit the benefit potentiality of improving the inertial response capability for various disturbances and provide less of a benefit for boosting the frequency nadir. This paper addresses an enhanced inertial response emulated control scheme for a DFIG to improve the maximum frequency deviation and maximum rate of change of frequency for various disturbances. To this end, the control coefficient is coupled with the system frequency deviation so as to regulate the control coefficient according to the system frequency deviation (i.e., sizes of the disturbance). Results clearly indicate that the proposed inertial response emulated control strategy provides better performance in terms of improving the maximum rate of change of frequency and maximum frequency deviation under various sizes of disturbance and random wind speed conditions.


Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1482
Author(s):  
Reiner Zorn ◽  
Paulina Szymoniak ◽  
Mohamed A. Kolmangadi ◽  
Richard Malpass-Evans ◽  
Neil B. McKeown ◽  
...  

The microscopic diffusion and the low frequency density of states (VDOS) of PIM-EA-TB(CH3) are investigated by inelastic and quasi-elastic neutron scattering where also the demethylated counterpart of PIM-EA-TB(H2) is considered. These intrinsic microporous polymers are characterized by large BET surface area values of several hundred m2/g and pore sizes between 0.5 and 2 nm. Detailed comparison is made to the archetype of polymers of intrinsic microporosity, PIM-1, and polynorbornenes also bearing a microporosity. Due to the wavelength of neutrons, the diffusion and vibrations can be addressed on microscopic length and time scales. From the inelastic neutron scattering experiments the low frequency density of states (VDOS) is estimated which shows excess contributions to the Debye-type VDOS known as Boson peak. It was found that the maximum frequency of the Boson peak decreases with increasing microporosity characterized by the BET surface area. However, besides the BET surface area, additional factors such as the backbone stiffness govern the maximum frequency of the Boson peak. Further the mean squared displacement related to microscopic motions was estimated from elastic fixed window scans. At temperatures above 175 K, the mean squared displacement PIM-EA-TB(CH3) is higher than that for the demethylated counterpart PIM-EA-TB(H2). The additional contribution found for PIM-EA-TB(CH3) is ascribed to the rotation of the methyl group in this polymer because the only difference between the two structures is that PIM-EA-TB(CH3) has methyl groups where PIM-EA-TB(H2) has none. A detailed comparison of the molecular dynamics is also made to that of PIM-1 and the microporous polynorbornene PTCNSi1. The manuscript focuses on the importance of vibrations and the localized molecular mobility characterized by the microscopic diffusion on the gas transport in polymeric separation membranes. In the frame of the random gate model localized fluctuations can open or close bottlenecks between pores to enable the diffusion of gas molecules. 


MAUSAM ◽  
2021 ◽  
Vol 58 (2) ◽  
pp. 153-160
Author(s):  
SAMARENDRA KARMAKAR ◽  
MD. MAHBUB ALAM

Attempts have been made to compute the precipitable water content of the troposphere, weighted average water vapour and to correlate these parameters with different instability indices and also with the next 24-hr rainfall, next 24-hr maximum rainfall and next 24-hr country averaged rainfall in order to predicting rainfall due to nor’westers in Bangladesh. It has been found that the maximum number of nor’westers occur when the precipitable water is 25-45 mm hr-1 between 1000 and 500 hPa, the maximum frequency being 48 in the range of 35-45 mm hr-1. The spatial distribution of precipitable water indicates that the maximum precipitable water is concentrated over the area near the places of nor’westers. The specific humidity has been found to increase on the dates of occurrence of nor’westers in Bangladesh on most occasions. Maximum number of nor’westers occurs when the weighted average specific humidity between the surface (1000 hPa) and 500 hPa is 8-12 g kg-1, the maximum frequency being 43 in the range of 8-10 g kg-1. The study reveals that nor’westers have been found to occur near or at the eastern end of maximum weighted average specific humidity. It has also been found that nor’westers occur near the point of inter-section of the axes of moist and dry zones. A number of parameters of the troposphere over Dhaka at 0000 UTC on the dates of occurrence of nor’westers such as precipitable water (mm/hr), MSWI, SWI, SWI/TT, (q1000 – q850) weighted averaged specific humidity have statistically significant correlations with next 24-hour rainfall at Dhaka, next 24-hour maximum rainfall in Bangladesh and country averaged rainfall. The correlation co-efficients are relatively small and the standard errors of estimates are higher. The small correlation co-efficients are significant because of the large number of data.


MAUSAM ◽  
2021 ◽  
Vol 58 (1) ◽  
pp. 67-74
Author(s):  
SAMARENDRA KARMAKAR ◽  
MD. MAHBUB ALAM

Attempts have been made to study the zonal and meridional fluxes of moisture of the troposphere prior to the occurrence of nor’westers in Bangladesh during the pre-monsoon season. The study reveals that the westerly fluxes (positive) of moisture (WFM) dominate in the troposphere over Dhaka at 0000 UTC from 925 to 200 hPa level having maximum frequency of WFM from 61.68 to 96.26% in the layer from 925 to about 300 hPa level. The maximum WFM over Dhaka at 0000 UTC on the dates of occurrence of nor’westers may be more than 200 gm kg-1 × ms-1 in the lower troposphere and the maximum easterly (negative) fluxes of moisture (EFM) over Dhaka at 0000 UTC may be -128.3 gm kg-1 × ms-1 at 1000 hPa. In the upper troposphere the zonal fluxes of moisture (ZFM) become nil in most of the cases. The ZFM over Dhaka at 0000 UTC are mainly westerly and more westerly in the lower and middle troposphere on the dates of occurrence of nor’westers as compared to the fluxes on the dates of non-occurrence. The southerly fluxes (positive) of moisture (SFM) dominate in the troposphere over Dhaka at 0000 UTC from 1000 to 300 hPa level. The meridional fluxes of moisture (MFM) are mainly southerly and more southerly in the lower and middle troposphere on the dates of occurrence of nor’westers as compared to the dates of non-occurrence. In the upper troposphere the MFM become nil in most of the cases.The vertically integrated ZFM and MFM from 1000 to 100 hPa over Dhaka at 0000 UTC on the dates of occurrence of nor’westers in Bangladesh have been computed, compared and inference has been drawn. The present study also deals with the spatial distribution of the vertically integrated ZFM and MFM from 925 to 400 hPa level over Bangladesh and its surrounding areas. The range of the vertically integrated ZFM and MFM for the layer is about (2-12) × 105 and (3-14) × 105 kg × ms-1 respectively over Bangladesh in most of the cases.


Author(s):  
Harish Thetanikkal Viswanathan ◽  
◽  
Prem Kumar John ◽  
Rajeev Vamadevan Rajalekshmi ◽  
◽  
...  

This work demonstrates estimation of critical reciprocating frequency of a fabricated linear pin-on-reciprocating plate tribometer by modal analysis. Experimental investigation by impact testing and numerical analysis using ANSYS Work bench 14 were performed to extract the modal parameters of individual subsystems. The authors could not find reported literature on of estimation of critical reciprocating frequency of pin-on-reciprocating plate tribometer. Authors developed a pin-onreciprocating plate tribometer that can simulate friction and wear under reciprocating sliding conditions for stroke lengths up to 150 mm. The developed pinon- reciprocating plate tribometer had a loading sub system, transmission subsystem and measurement subsystem. From experimental and numerical estimation of modal parameters, transmission subsystem found to had the lowest modal frequency of 18 Hz. Maximum frequency of reciprocation then fixed at 30% of the lowest modal frequency of 18 Hz that is 5 Hz. Confirmatory friction tests were then conducted on the tribometer and found that identification of maximum frictional force was difficult when the reciprocating frequency of plate of tribometer exceeded 4 Hz due to vibrations in measuring system and agreed with the reported literature. This work addresses the need of methodology for establishing critical reciprocating frequency of tribometer. This paper elaborates the modal analysis of a fabricated linear reciprocating tribometer. Resonance of subsystems in reciprocating tribometer affects experimental estimate of coefficient of friction (CoF). Subsystems have their own individual modal frequencies. Hence, modal analysis of all subsystems becomes obligatory. Tribometer developed for this study can simulate reciprocating friction and wear for stroke lengths up to 150 mm. Experimental and numerical analysis utilized to identify modal frequency of individual subsystems. Tests identified that transmission subsystem had the lowest modal frequency of 18 Hz. Maximum frequency of reciprocation then fixed at 4Hz. This is 25% of the lowest modal frequency of 18 Hz as delineated in literature. Confirmatory friction tests then conducted on the tribometer. Resolving maximum frictional force along the stroke length was impossible over 4 Hz of reciprocating frequency. This is 25% of the lowest modal frequency of structure and agreed with the reported literature. Authors sincerely hope the methodology used in this paper will guide fellow researchers for modal analysis of reciprocating tribometer.


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