39,558 research outputs found
A study of project planning on Libyan construction projects
Construction projects are regularly faced by scheduling problems causing the projects to finish beyond their predetermined due date; this is a global phenomenon. The main purpose of this study is to consider the problems associated with project planning generally, with specific reference to construction projects in Libya. This study is unique in two respects. First, despite the recent high volume of infrastructure work in the country, there have been few investigations into construction delays in Libya. Secondly, earlier studies have considered the causes or the effects of project delays, whereas the present aim is to evaluate the potential of applying a planning and scheduling technique that is entirely novel in the Libyan context. The paper reports the results of Phase I of this research
Efficient FPGA implementation of high-throughput mixed radix multipath delay commutator FFT processor for MIMO-OFDM
This article presents and evaluates pipelined architecture designs for an improved high-frequency Fast Fourier
Transform (FFT) processor implemented on Field Programmable Gate Arrays (FPGA) for Multiple Input Multiple Output
Orthogonal Frequency Division Multiplexing (MIMO-OFDM). The architecture presented is a Mixed-Radix Multipath Delay
Commutator. The presented parallel architecture utilizes fewer hardware resources compared to Radix-2 architecture,
while maintaining simple control and butterfly structures inherent to Radix-2 implementations. The high-frequency
design presented allows enhancing system throughput without requiring additional parallel data paths common in
other current approaches, the presented design can process two and four independent data streams in parallel
and is suitable for scaling to any power of two FFT size N. FPGA implementation of the architecture demonstrated
significant resource efficiency and high-throughput in comparison to relevant current approaches within
literature. The proposed architecture designs were realized with Xilinx System Generator (XSG) and evaluated
on both Virtex-5 and Virtex-7 FPGA devices. Post place and route results demonstrated maximum frequency
values over 400 MHz and 470 MHz for Virtex-5 and Virtex-7 FPGA devices respectively
Improving latency tolerance of multithreading through decoupling
The increasing hardware complexity of dynamically scheduled superscalar processors may compromise the scalability of this organization to make an efficient use of future increases in transistor budget. SMT processors, designed over a superscalar core, are therefore directly concerned by this problem. The article presents and evaluates a novel processor microarchitecture which combines two paradigms: simultaneous multithreading and access/execute decoupling. Since its decoupled units issue instructions in order, this architecture is significantly less complex, in terms of critical path delays, than a centralized out-of-order design, and it is more effective for future growth in issue-width and clock speed. We investigate how both techniques complement each other. Since decoupling features an excellent memory latency hiding efficiency, the large amount of parallelism exploited by multithreading may be used to hide the latency of functional units and keep them fully utilized. The study shows that, by adding decoupling to a multithreaded architecture, fewer threads are needed to achieve maximum throughput. Therefore, in addition to the obvious hardware complexity reduction, it places lower demands on the memory system. The study also reveals that multithreading by itself exhibits little memory latency tolerance. Results suggest that most of the latency hiding effectiveness of SMT architectures comes from the dynamic scheduling. On the other hand, decoupling is very effective at hiding memory latency. An increase in the cache miss penalty from 1 to 32 cycles reduces the performance of a 4-context multithreaded decoupled processor by less than 2 percent. For the nondecoupled multithreaded processor, the loss of performance is about 23 percent.Peer ReviewedPostprint (published version
Development of a scale for factors causing delays in infrastructure projects in India
The objective of the paper is to develop a validated scale to measure the factors that cause delays in infrastructure projects. The study employed a standard three phase scale development procedure of Churchill (1979) which was augmented subsequently by Nunnally, Bernstein and Berge (1994) and Prakash and Phadtare (2018). In phase one, 73 factors that cause delays were identified, which were reduced to 45 based on literature review and expert opinions. These 45 factors were subjected to an exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) in phase two and three, respectively, to refine and establish convergent, discriminant and nomological validity of the scale. The study confirms that delays in infrastructure projects happen due to six factors, i.e., Contractor Related Factors (CON); Consultant Related Factors (CS); External Factors (EX); Labour Related Factors (LR); Material Related Factors (MT) and Design Related Factors (DJ). The study is particularly useful for the firms engaged in the development of infrastructure projects globally, as it identifies and ranks the factors that cause delays in a project. However, the study being confirmatory in nature only confirms the grouping of factors causing delays and is also limited by the possibility of sampling error. 
funcX: A Federated Function Serving Fabric for Science
Exploding data volumes and velocities, new computational methods and
platforms, and ubiquitous connectivity demand new approaches to computation in
the sciences. These new approaches must enable computation to be mobile, so
that, for example, it can occur near data, be triggered by events (e.g.,
arrival of new data), be offloaded to specialized accelerators, or run remotely
where resources are available. They also require new design approaches in which
monolithic applications can be decomposed into smaller components, that may in
turn be executed separately and on the most suitable resources. To address
these needs we present funcX---a distributed function as a service (FaaS)
platform that enables flexible, scalable, and high performance remote function
execution. funcX's endpoint software can transform existing clouds, clusters,
and supercomputers into function serving systems, while funcX's cloud-hosted
service provides transparent, secure, and reliable function execution across a
federated ecosystem of endpoints. We motivate the need for funcX with several
scientific case studies, present our prototype design and implementation, show
optimizations that deliver throughput in excess of 1 million functions per
second, and demonstrate, via experiments on two supercomputers, that funcX can
scale to more than more than 130000 concurrent workers.Comment: Accepted to ACM Symposium on High-Performance Parallel and
Distributed Computing (HPDC 2020). arXiv admin note: substantial text overlap
with arXiv:1908.0490
A Scalable Low-Cost-UAV Traffic Network (uNet)
This article proposes a new Unmanned Aerial Vehicle (UAV) operation paradigm
to enable a large number of relatively low-cost UAVs to fly
beyond-line-of-sight without costly sensing and communication systems or
substantial human intervention in individual UAV control. Under current
free-flight-like paradigm, wherein a UAV can travel along any route as long as
it avoids restricted airspace and altitudes. However, this requires expensive
on-board sensing and communication as well as substantial human effort in order
to ensure avoidance of obstacles and collisions. The increased cost serves as
an impediment to the emergence and development of broader UAV applications. The
main contribution of this work is to propose the use of pre-established route
network for UAV traffic management, which allows: (i) pre- mapping of obstacles
along the route network to reduce the onboard sensing requirements and the
associated costs for avoiding such obstacles; and (ii) use of well-developed
routing algorithms to select UAV schedules that avoid conflicts. Available
GPS-based navigation can be used to fly the UAV along the selected route and
time schedule with relatively low added cost, which therefore, reduces the
barrier to entry into new UAV-applications market. Finally, this article
proposes a new decoupling scheme for conflict-free transitions between edges of
the route network at each node of the route network to reduce potential
conflicts between UAVs and ensuing delays. A simulation example is used to
illustrate the proposed uNet approach.Comment: To be submitted to journal, 21 pages, 9 figure
Survey on wireless technology trade-offs for the industrial internet of things
Aside from vast deployment cost reduction, Industrial Wireless Sensor and Actuator Networks (IWSAN) introduce a new level of industrial connectivity. Wireless connection of sensors and actuators in industrial environments not only enables wireless monitoring and actuation, it also enables coordination of production stages, connecting mobile robots and autonomous transport vehicles, as well as localization and tracking of assets. All these opportunities already inspired the development of many wireless technologies in an effort to fully enable Industry 4.0. However, different technologies significantly differ in performance and capabilities, none being capable of supporting all industrial use cases. When designing a network solution, one must be aware of the capabilities and the trade-offs that prospective technologies have. This paper evaluates the technologies potentially suitable for IWSAN solutions covering an entire industrial site with limited infrastructure cost and discusses their trade-offs in an effort to provide information for choosing the most suitable technology for the use case of interest. The comparative discussion presented in this paper aims to enable engineers to choose the most suitable wireless technology for their specific IWSAN deployment
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