Could Alfa fibers substitute glass fibers in composite materials?

In the present work polyester resin composites with Alfa fibers in the form of pulp were prepared and their properties were compared with those of polyester resin reinforced with glass fibers, the latter composites being widely used for structural applications. The composites were prepared using two manufacturing processes, namely hand lay-up and vacuum molding, to assess the influence of the process on the composites properties. Firstly, the tensile properties for the two composites were evaluated. The composites thermal properties were studied by differential scanning calorimetry and thermogravimetric analysis. Finally, the morphology of a glass fiber composite (GFC) and Alfa pulp composite (APC) was analyzed by scanning electron microscopy, to characterize the composites surface and cross-sections.The authors would like to thank CTC (Centre technique de la Chimie) for their valuable help during mechanical testing. The company Solutions Composites, especially Mr.Adel Hammami is gratefully acknowledged for financial and material support. The authors also wish to thank the members of the Department of Polymer Engineering University of Minho, Guimarães, Portugal for their valuable cooperation. This research work is carried out as part of a mobidocPhD, a program financed by the European Union within Pasri Projet. M.C Paiva acknowledges the Portuguese Foundation for Science and Technology (FCT) and the European program FEDER/COMPETE for the financial support through project PEst-C/CTM/ LA0025/2013 (LA 25-2015-2017)

Philip F. Kennedy (éd.), On Fiction and Adab in Medieval Arabic Literature

L’ouvrage recensé ici reprend les communications faites dans le cadre du « Workshop  in  Medieval Arabic Literature » qui s’est tenu les 21 et 22 avril 2000 à l’université de New York (Department of Middle Eastern Studies). Il est dédié à la mémoire de Rina Drory. Le thème de cet atelier était « Defining Fiction and Adab in Medieval Arabic Literature ». Ces communications sont au nombre de dix. Elles sont toutes suivies d’une bibliographie, certaines d’annexes. En voici les titres et les noms..

Design and evaluation of buffered triple modular redundancy in interleaved-multi-threading processors

Fault management in digital chips is a crucial aspect of functional safety. Significant work has been done on gate and microarchitecture level triple modular redundancy, and on functional redundancy in multi-core and simultaneous-multi-threading processors, whereas little has been done to quantify the fault tolerance potential of interleaved-multi-threading. In this study, we apply the temporal-spatial triple modular redundancy concept to interleaved-multi-threading processors through a design solution that we call Buffered triple modular redundancy, using the soft-core Klessydra-T03 as the basis for our experiments. We then illustrate the quantitative findings of a large fault-injection simulation campaign on the fault-tolerant core and discuss the vulnerability comparison with previous representative fault-tolerant designs. The results show that the obtained resilience is comparable to a full triple modular redundancy at the cost of execution cycle count overhead instead of hardware overhead, yet with higher achievable clock frequency

Caractérisation de l'écoulement dans un convergent à paroi courbée

Un travail numérique est conduit pour l'analyse de l'écoulement dans un convergent monté sur un dispositif expérimental destiné à la production de la parole. L'effet de la forme de la paroi est étudié quant à son influence sur le taux d'uniformité dynamique et sur les pertes de charge. L'analyse révèle l'existence d'un antagonisme entre l'aplatissement de la paroi en sortie de convergent et sa courbure dans la zone amont au col géométrique

Klessydra-T: Designing Vector Coprocessors for Multi-Threaded Edge-Computing Cores

Computation intensive kernels, such as convolutions, matrix multiplication and Fourier transform, are fundamental to edge-computing AI, signal processing and cryptographic applications. Interleaved-Multi-Threading (IMT) processor cores are interesting to pursue energy efficiency and low hardware cost for edge-computing, yet they need hardware acceleration schemes to run heavy computational workloads. Following a vector approach to accelerate computations, this study explores possible alternatives to implement vector coprocessing units in RISC-V cores, showing the synergy between IMT and data-level parallelism in the target workloads.Comment: Final revision accepted for publication on IEEE Micro Journa

A RISC-V fault-tolerant soft-processor based on full/partial heterogeneous dual-core protection

The low probability of single event upsets (SEU) within particular satellite orbits, makes Commercial-off-the-shelf (COTS) electronic components a viable solution for space system implementation, thanks to the introduction of design-level fault tolerance techniques at the expense of some performance/energy/area penalty. This paper illustrates the design and validation of a novel RISC-V dual-core architecture, based on a computing paradigm that we refer to as full/partial heterogeneous multi-core protection. The approach relies on a small, low-performance, fully fault-tolerant core (LP core) coupled with a high-performance partially fault-tolerant core (HP core). The computing paradigm assumes the failure-exposed HP core executes computation intensive routines for relatively short periods of time, making the occurrence of failures a statistically unlikely situation, while the fully fault-tolerant LP core operates in critical control tasks and manages the failure recovery of the high-performance core. The execution time percentage in the LP core varies from a minimum of 11.4% up to a maximum of 91.3% while in the HP core it is between 8.7% and 88.6%, depending on the application. In the proposed study, both the cores belong to the RISC-V compliant Klessydra core family. The dual-core architecture also includes a watchdog timer controlled by the LP core and monitoring the non-protected HP core, and a context switch FIFO that speeds up the code and data switch between the two cores during failure recovery. A dedicated run-time software environment coordinates the execution of tasks on the high-performance core in a resilient fashion. The dual-core processor has been validated through extensive RTL simulations running in an UVM-based fault-injection environment, which emulates SEUs at various rates. Experimental results illustrate the benefits and limits obtained by using a heterogeneous architecture with different levels of protection and performance. The failure probability assuming a SEU fault occurrence can be reduced by a factor between 10X and 30X with respect to the non-protected architecture, leading to an average failure rate of up to 4.00E-06 per second with respect to 1.80E-05 per second in the non-protected architecture

Dynamic triple modular redundancy in interleaved hardware threads: an alternative solution to lockstep multi-cores for fault-tolerant systems

Over the years, significant work has been done on high-integrity systems, such as those found in cars, satellites and aircrafts, to minimize the risk that a logic fault causes a system failure, thus having functional safety as a key requirement. In this study, we employ an innovative approach to harness the benefits of both Dual Modular Redundancy and Triple Modular Redundancy techniques within an Interleaved-Multi-Threading microprocessor core, by means of a microarchitecture design capable of dynamically switching from Dual Modular Redundancy to Triple Modular Redundancy in case of faults. We explain the quantitative results obtained from an extensive fault injection simulation campaign on the fault tolerant core compared with its previous version regarding fault tolerant capabilities. The results show that in several application cases the fault resilience improvement and the hardware and timing overhead are better compared to the lockstep-based dual core approach. The proposed technique achieves 98,6% fault mitigation at the expense of only 4 clock cycles for roll-back overhead, with no checkpointing redundancy

Design, implementation and evaluation of a new variable latency integer division scheme

Integer division is key for various applications and often represents the performance bottleneck due to its inherent mathematical properties that limit its parallelization. This paper presents a new data-dependent variable latency division algorithm derived from the classic non-performing restoring method. The proposed technique exploits the relationship between the number of leading zeros in the divisor and in the partial remainder to dynamically detect and skip those iterations that result in a simple left shift. While a similar principle has been exploited in previous works, the proposed approach outperforms existing variable latency divider schemes in average latency and power consumption. We detail the algorithm and its implementation in four variants, offering versatility for the specific application requirements. For each variant, we report the average latency evaluated with different benchmarks, and we analyze the synthesis results for both FPGA and ASIC deployment, reporting clock speed, average execution time, hardware resources, and energy consumption, compared with existing fixed and variable latency dividers

Mental illness stigma as a moderator in the relationship between religiosity and help-seeking attitudes among Muslims from 16 Arab countries

Background: Determining the potential barriers responsible for delaying access to care, and elucidating pathways to early intervention should be a priority, especially in Arab countries where mental health resources are limited. To the best of our knowledge, no previous studies have examined the relationship between religiosity, stigma and help-seeking in an Arab Muslim cultural background. Hence, we propose in the present study to test the moderating role of stigma toward mental illness in the relationship between religiosity and help-seeking attitudes among Muslim community people living in different Arab countries. Method: The current survey is part of a large-scale multinational collaborative project (StIgma of Mental Problems in Arab CounTries [The IMPACT Project]). We carried-out a web-based cross-sectional, and multi-country study between June and November 2021. The final sample comprised 9782 Arab Muslim participants (mean age 29.67 ± 10.80 years, 77.1% females). Results: Bivariate analyses showed that less stigmatizing attitudes toward mental illness and higher religiosity levels were significantly associated with more favorable help-seeking attitudes. Moderation analyses revealed that the interaction religiosity by mental illness stigma was significantly associated with help-seeking attitudes (Beta =.005; p \u3c.001); at low and moderate levels of stigma, higher religiosity was significantly associated with more favorable help-seeking attitudes. Conclusion: Our findings preliminarily suggest that mental illness stigma is a modifiable individual factor that seems to strengthen the direct positive effect of religiosity on help-seeking attitudes. This provides potential insights on possible anti-stigma interventions that might help overcome reluctance to counseling in highly religious Arab Muslim communities