Time-sharing Approach Research Articles

Design and analysis of a switch fault-tolerant multi-input single-output DC-DC converter for high reliability applications

The DC–DC converters have been used extensively in various industrial applications such as consumer electronics, aerospace, electric vehicles, and renewable energy systems. The reliability ensures that the converter continues to operate safely and efficiently despite the presence of faults. Enhancing the reliability of DC-DC converters is a challenging task, as power switches are the most fragile components that can be affected by faults in the system. Hence, to address these challenges and ensure the safety of the converter, it is vital to implement appropriate fast fault-diagnosis techniques and fault-tolerant strategies. Many new network topologies have been presented in literature, which lead to a shift from single input–single output to multiport converters. These converters are suitable for integrating different energy sources. However, the majority of them are operated using a time-sharing method, in which only one energy source is used at a time, and the others are inactive at any specified duty cycle. Therefore, the converter and input sources are underutilized in the conventional time-sharing approach. This paper proposes a new multi-input single-output (MISO) converter topology with fully integrated switch fault tolerance. It can perform multi-input buck, boost, and buck-boost operations. More importantly, the converter can operate uninterruptedly for single or multiple switch faults. Using simulation and experimental results, a 400 W prototype circuit is designed to analyze the converter's reliability and performance.

Area-Time-Efficient Scalable Schoolbook Polynomial Multiplier for Lattice-Based Cryptography

Lattice-based cryptography (LBC) stands out as one of the most viable classes of quantum-resistant schemes. This brief explores a time-sharing approach, with different parallelism levels, for a crucial operation in LBC cryptosystems, i.e., polynomial multiplication. We also employ an innovative coefficient ordering method in our time-shared schoolbook polynomial multiplication (SPM) to combine the best of two worlds: design compactness and lower processing latency. Thus, our work offers a choice of design points with performance vs. resource trade-offs. Our fastest proposed design exhibits 80% and 57% reductions in LUTs and throughput, respectively, compared to the existing fully parallel SPM architecture (on Xilinx Ultrascale+), which lead to a 53% improvement in the area-time-product efficiency. Our smallest proposed design is more than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.2\times $ </tex-math></inline-formula> faster than the existing low-cost parallel SPM architecture (on Xilinx Kintex-7) at the expense of 85% additional area resources.

Selfish Routing Game-Based Multi-Resource Allocation and Fair Scheduling of Indivisible Jobs in Edge Environments

Distributed and heterogeneous edge computing environments require efficient allocation and scheduling of multiple users’ applications. This paper presents a game-theoretic solution to model the competition between time-sensitive internet of things (IoT) applications with indivisible loads to be allocated and scheduled to edge servers. We model the allocation problem as a selfish routing game such that no job is unsatisfied with its allocation. Also, the allocated jobs are scheduled using a weighted time-sharing approach, which assigns resources to jobs proportional to their demands and deadlines. We proved the existence of pure Nash equilibrium in the introduced game and presented a greedy and polynomial time algorithm to obtain the solution called SAFSA. Using an extended version of the CloudSim simulator, we assess our approach in different situations by employing a real-world dataset of the Google cluster. Since the proposed algorithm considers jobs’ deadlines beside resource requests in allocation and scheduling decisions, it can simultaneously minimize average response time and maximize the number of jobs completed within their deadlines.The simulation results confirm the ability of SAFSA to efficiently execute the jobs within their deadlines, especially when there are many IoT devices and edge servers in the system, which is the main characteristic of IoT environments.

SoftHM: A Software-Based Hierarchical Modulation Design for Wireless System

Hierarchical Modulation (HM) is quite efficient for multimedia broadcast in wireless networks. It exploits the wireless broadcast advantage and allows a transmission to reach different users with various qualities. However, existing HM related schemes are based on specially designed hardware, leading to extra hardware and deployment cost in practice. As a remedy for this, we design and implement a software-based HM scheme, named as SoftHM. By carefully tuning the Physical Layer input of a packet (a sequence of “0” or “1” bits, known as PHY payload), a transmitter simply broadcasts the packet with a single rate (e.g., 54Mbps, the highest rate in 802.11g WLAN), while diverse receivers can decode and extract different amount of information (with different reception rate, e.g., 12Mbps or 54Mbps) from it based on their link qualities. Reverse engineering techniques are adopted so that SoftHM works in a plug-in mode, offering it high potentials for wireless systems without any changes in existing modulation and coding modules. We implement SoftHM based on Universal Software Radio Peripheral (USRP) B210 and Commercial of the Shelf (COTS) Wi-Fi devices. Both rigorous analysis on its performance and comprehensive implementation-based experiments show that compared with the traditional time-sharing approach, to support low-quality users with the same bandwidth, high-quality users in SoftHM achieve 111.1% to 616.7% higher throughput. Likewise, to serve high-quality users with the same bandwidth, low quality users in softHM achieve 176.9% to 390.9% higher throughput.

NODIC: a novel distributed clustering routing protocol in WSNs by using a time-sharing approach for CH election

Due to the battery limitations, energy-efficient routing is one of the most important issues in WSNs. In this paper, a novel distributed clustering routing protocol (NODIC) is proposed. The algorithm makes three main contributions to literature. Firstly, a time-sharing approach for CH election is suggested differently from the studies in literature. The most effective parameters are combined in a time-sharing approach on the purpose of gaining the highest performance. Secondly, easy implementation and self-reliant decision of probabilistic schemes and the guarantee that iterative schemes issue about selecting the desired CHs are pieced together without using any of them. Finally, since CH decision is performed locally and dynamically, the clusters can make their decisions independently from the others. NODIC is compared with three common corresponding approaches in literature for various values of the number of nodes and under different traffic distributions. The algorithms are evaluated by using the number of living nodes and total energy consumptions per round. The results show that NODIC performs considerably better than the other approaches for all number of nodes and under all distributions up to 79 %.

Static and dynamic job scheduling with communication aware policy in cluster computing

Parallel jobs submitted to processors should be efficiently scheduled to achieve high performance. Early scheduling strategies for parallel jobs make use of either space-sharing approach or time-sharing approach. The scheduling strategy proposed in this work, makes use of both the policies for parallel jobs while scheduling under clusters. Static and dynamic scheduling algorithms were developed for communication intensive jobs. The algorithms are used to handle different types of jobs such as serial, parallel and mixed jobs. For performance evaluation, the workload from Grid5000 platform is considered. The main objective is to achieve performance and power improvement. The dynamic scheduling algorithm with communication aware policy gives better performance when compared to static scheduling algorithm that is tested under the given workload.

Relay Assisted Physical Resource Sharing: Projection Based Separation of Multiple Operators (ProBaSeMO) for Two-Way Relaying With MIMO Amplify and Forward Relays

In this paper, we investigate a relay-assisted resource sharing scenario, namely, multi-operator two-way relaying with a MIMO amplify-and-forward (AF) relay. Here, the spectrum and the relay (infrastructure) are shared among multiple operators. We develop the projection based separation of multiple operators (ProBaSeMo) relay transmit strategy, which is inspired by the block diagonalization (BD) and regularized block diagonalization (RBD) schemes that are space-division multiple access (SDMA) approaches for multi-user MIMO systems. If the user terminals are equipped with multiple antennas, appropriate precoding and decoding matrix designs are also proposed. Compared to the time-shared approach where the relay is used by different operators in a time division multiple access (TDMA) manner, we demonstrate that the ProBaSeMO algorithms can provide a significant sharing gain in terms of the sum rate with many antennas at the relay or in the high SNR regime in a two-operator case. For a fixed number of antennas at the relay, an even higher sharing gain can be obtained if the number of operators increases.

Bits Through Deterministic Relay Cascades With Half-Duplex Constraint

Consider a relay cascade, i.e. a network where a source node, a sink node and a certain number of intermediate source/relay nodes are arranged on a line and where adjacent node pairs are connected by error-free (q+1)-ary pipes. Suppose the source and a subset of the relays wish to communicate independent information to the sink under the condition that each relay in the cascade is half-duplex constrained. A coding scheme is developed which transfers information by an information-dependent allocation of the transmission and reception slots of the relays. The coding scheme requires synchronization on the symbol level through a shared clock. The coding strategy achieves capacity for a single source. Numerical values for the capacity of cascades of various lengths are provided, and the capacities are significantly higher than the rates which are achievable with a predetermined time-sharing approach. If the cascade includes a source and a certain number of relays with their own information, the strategy achieves the cut-set bound when the rates of the relay sources fall below certain thresholds. For cascades composed of an infinite number of half-duplex constrained relays and a single source, we derive an explicit capacity expression. Remarkably, the capacity in bits/use for q=1 is equal to the logarithm of the golden ratio, and the capacity for q=2 is 1 bit/use.

Crystallized Rate Regions for MIMO Transmission

When considering the multiuser SISO interference channel, the allowable rate region is not convex and the maximization of the aggregated rate of all the users by the means of transmission power control becomes inefficient. Hence, a concept of the crystallized rate regions has been proposed, where the time-sharing approach is considered to maximize the sumrate. In this paper, we extend the concept of crystallized rate regions from the simple SISO interference channel case to the MIMO/OFDM interference channel. As a first step, we extend the time-sharing convex hull from the SISO to the MIMO channel case. We provide a non-cooperative game-theoretical approach to study the achievable rate regions, and consider the Vickrey-Clarke-Groves (VCG)mechanism design with a novel cost function. Within this analysis, we also investigate the case of OFDM channels, which can be treated as the special case of MIMO channels when the channel transfer matrices are diagonal. In the second step, we adopt the concept of correlated equilibrium into the case of two-user MIMO/OFDM, and we introduce a regret-matching learning algorithm for the system to converge to the equilibrium state. Moreover, we formulate the linear programming problem to find the aggregated rate of all users and solve it using the Simplex method. Finally, numerical results are provided to confirm our theoretical claims and show the improvement provided by this approach.

Glucose effects on cytoplasmic Ca2+ of individual pancreatic beta-cells recorded by two procedures for dual-wavelength fluorometry.

Two different dual-wavelength microfluorometric systems were used to measure the cytoplasmatic Ca2+ concentration (Cai2+) of individual pancreatic beta-cells loaded with the indicator fura-2. Fluorescence was excited continuously at 340 nm with frequent manual checks at 360 nm. Alternatively, the 340/380 nm fluorescence excitation ratio was recorded based on automated samples at the two wavelengths every 10 msec. Irrespective of the experimental technique a rise of the glucose concentration from 3 to 20 mM resulted in an initial lowering of Cai2+ followed by a rise with a peak and a subsequent sustained intermediary level. The increase of Cai2+ depended on the presence of extracellular Ca2+. In some cells the pattern differed and the increase of the glucose concentration induced large oscillations of Cai2+. Glucose-induced increase of Cai2+ was associated with small rapid fluctuations, which were detectable only with the fast time-sharing approach. The characteristic Cai2+ response to glucose was maintained by some beta-cells after culture for more than 3 weeks. The results indicate that the glucose sensitivity of individual beta-cells varies, and that many electrically coupled cells within an islet collectively determine the characteristic pattern of rhythmic depolarization.

Simultaneous detection of amide and methyl correlations using a time shared NMR experiment: application to binding epitope mapping

Simultaneous recording of different NMR parameters is an efficient way to reduce the overall experimental time and speed up structural studies of biological macromolecules. This can especially be beneficial in the case of fast NMR-based drug screening applications or for collecting NOE restraints, where prohibitively long data collection time may be required. We have developed a novel pulse sequence element that enables simultaneous detection of amide (15)N, (1)H and methyl (13)C, (1)H correlations. The coherence selection for the (15)N spins can be obtained using the gradient selected and coherence order selective coherence transfer, whereas the hypercomplex (States) method is simultaneously employed for the (13)C coherence selection. Experimental verification of proposed time-shared approach for simultaneous detection amide (15)N, (1)H and methyl (13)C, (1)H correlations has been carried out with three proteins, human ubiquitin, SH3 domain of human epidermal growth factor receptor pathway substrate 8-like protein (Eps8L1) and maltose binding protein complex with beta-Cyclodextrin. In addition, the proposed methodology was applied for ligand binding site mapping on SH3 domain of Eps8L1, using uniformly (15)N and fractionally (10%) (13)C labeled sample. Our results show that the proposed time-shared (15)N/(13)C-HSQC affords significant time saving (or improved sensitivity) in establishing (15)N, (1)H and methyl (13)C, (1)H correlations, thus making it an attractive building block for 3D and 4D dimensional applications. It is also a very efficient tool in protein ligand interaction studies even when combined with cost-effective labeling scheme with uniform (15)N and 10% fractional (13)C enrichment.

Single Code-Based Dynamic Grouping with Cycle Interleaving Algorithm for Reducing Waste Rate in WCDMA Cellular Networks

3G must offer high data rates since it should support real-time multimedia services; one performance enhancement, the use of the OVSF code tree, has adopted in 3G WCDMA networks. Unfortunately, this technique allows the link capacity to be set at the base rate times powers of two. This results in wasting bandwidth while the required rate is not powers of two of the basic rate. Several multi-code assignment mechanisms have been proposed to reduce the waste rate, but incur some drawbacks, including high complexity of handling multiple codes and increasing cost of using more rake combiners. Our solution is a dynamic grouping code assignment that allows any rate to be achieved with a single code for any possible rate of traffic. The dynamic grouping approach first forms several calls into a group. It then allocates a subtree to the group and dynamically shares the subtree codes based on time-sharing of slots within a group cycle time. The waste rate and code blocking is thus reduced significantly. Since transmission delay and jitter may occur in such a time-sharing approach, two schemes of cycle interleaving are proposed to minimize delay and jitter. Numerical results demonstrate that the proposed approach reduces the waste rate and increases the system utilization obviously, and the proposed cycle interleaving schemes minimizes delay and jitter significantly.

An Efficient Adaptive Grouping for Single Code Assignment in WCDMA Mobile Networks

For achieving high utilization and efficient code management of the OVSF code tree in 3G WCDMA networks, several researches have extensively studied. Based on combining both the code assignment and the reassignment mechanisms, it increases obviously high utilization and reduces completely the code blocking. Nevertheless, the required rate of traffic should be powers of two of the basic rate, i.e. 1R, 2R, 4R, ?, etc., which is impractical and results in wasting the system bandwidth while the required rate is not powers of two of the basic rate. Several multi-code assignment mechanisms have proposed to reduce the waste rate. Nevertheless, these methods bring two inevitable drawbacks including, high complexity of handling multiple codes, and increasing the cost of using more rake combiners at both the base stations and mobile nodes. Therefore, we propose an adaptive grouping code assignment herein to provide a single channelization code for any possible rate of traffic, even though the required rate is not powers of two of the basic rate. Based on the dynamic programming algorithm, the adaptive grouping approach forms several calls into a group. Then it allocates a subtree to the group and adaptively shares the subtree codes for these calls in the concept of time-sharing of slots during a group cycle time. Therefore, the waste rate and code blocking are thus reduced obviously while using a single rake combiner. Since the delay problem may be occurred in such a time-sharing approach, we propose two schemes of cycle interleaving methods to reduce delay. Numerical results indicate that the proposed adaptive grouping approach reduces significantly the waste rate and thus increases the system utilization. Moreover, the proposed cycle interleaving scheme reduces data delay significantly.

Loosely coordinated coscheduling in the context of other approaches for dynamic job scheduling: a survey

Loosely coordinated (implicit/dynamic) coscheduling is a time-sharing approach that originates from network of workstations environments of mixed parallel/serial workloads and limitedsoftware suppo...

Loosely coordinated coscheduling in the context of other approaches for dynamic job scheduling: a survey

Loosely coordinated (implicit/dynamic) coscheduling is a time-sharing approach that originates from network of workstations environments of mixed parallel/serial workloads and limitedsoftware support. It is meant to be an easy-to-implement and scalable approach. Considering that the percentage of clusters in parallel computing is increasing and easily portable software is needed, loosely coordinated coscheduling becomes an attractive approach for dedicated machines. Loose coordination offers attractive features as a dynamic approach. Static approaches for local job scheduling assign resources exclusively and non-preemptively. Such approaches still remain beyond the desirable resource utilization and average response times. Conversely, approaches for dynamic scheduling of jobs can preempt resources and/or adapt their allocation. They typically provide better resource utilization and response times. Existing dynamic approaches are full preemption with checkpointing, dynamic adaptation of node/CPU allocation, and time sharing via gang or loosely coordinated coscheduling. This survey presents and compares the different approaches, while particularly focusing on the less well-explored loosely coordinated time sharing. The discussion particularly focuses on the implementation problems, in terms of modification of standard operating systems, the runtime system and the communication libraries. Copyright © 2005 John Wiley & Sons, Ltd.

Beyond the mainframe: a guide to open computer systems

From the Publisher: No terms in computing are more pervasive and less understood than Open Systems and Client/Server. The technology-shift away from centralized, often mainframe-based systems towards the distributed client/server model characterizes computing in the 1990s and is, in large part, made possible by standardised open system components. If you have responsibility for management, procurement or implementation of a modern computer system, you need to be aware of open systems and client/server, the technologies they encapsulate and their importance to you. This book provides a complete overview of computer hardware and software technology, emerging trends and the impact of open systems and the client/server model on the enterprise's business decisions and practices. On reading it, you will be able to define the term 'Client/Server Architecture'; define the term 'Open Systems'; compare the relative strengths and weaknesses of the client/server model and the traditional timesharing approach; understand the developments in computer hardware, operating systems, networks and application software which have led the move to smaller distributed systems; assess the opportunities presented by Client/Server and the pitfalls inherent in implementing it; evaluate current client and server applications; better predict future trends in distributed computing technologies, and understand the benefits of the new computing model for your enterprise and your customers.

Interaction of hunger and sexual motivation in the male rat: A time-sharing approach

To examine the interaction of hunger and sexual motivation, male rats were given sexual behaviour tests under 0, 24, and 48 h of food deprivation. Each male was placed with an oestrous-induced female and allowed to copulate until sexual exhaustion. Food was freely available throughout the test period. Mount and intromission latencies increased under both levels of food deprivation, but neither ejaculation frequency nor any of the other fourteen measures of sexual behaviour were altered under deprivation conditions. There was a decreased latency to start eating, an increase in time spent eating, and an increase in the amount of food eaten with increased food deprivation. The frequency of feeding bouts increased, but the duration of feeding bouts was constant over deprivation conditions. Under food deprivation, animals shifted from sexual behaviour to feeding more frequently than when they were non-deprived. These shifts occurred primarily during periods of low sexual arousal. The majority of feeding occurred during the post-ejaculatory intervals. Bouts of sexual behaviour were not usually interrupted by bouts of feeding. This pattern suggests that feeding and sexual activity occur on a time-sharing basis with sexual behaviour as the dominant activity.