Hierarchical coherency management for shared virtual memory multicomputers

In this paper., a hierarchical energy management strategy for a community of multiple smart homes is proposed. This strategy reduces the stress on the power grid caused by uncoordinated energy scheduling of smart homes. Different stochastic operational conditions for plug-in electric vehicles (PEVs)and household battery storages are considered. First., cost-effective day-ahead energy schedules under these operational conditions are calculated by individual home energy management systems (HEMSs). Then., a centralized decision making unit determines the day-ahead schedule for each household with the aim of reducing the stress on the grid. Comprehensive results obtained from simulations show that the proposed hierarchical energy management strategy not only maintains a low energy purchase cost for each individual household., but also smooths the overall grid power profile requested by all smart homes combined.

For 5G base stations equipped with multiple energy sources, such as energy storage systems (ESSs) and photovoltaic (PV) power generation, energy management is crucial, directly influencing the operational cost. Hence, aiming at increasing the utilization rate of PV power generation and improving the lifetime of the battery, thereby reducing the operating cost of the base station, a hierarchical energy management strategy based on the improved dung beetle optimization (IDBO) algorithm is proposed in this paper. The first control layer provides bus voltage control to each power module. In the second control layer, a dynamic balance control strategy calculates the power of the ESSs using the proportional–integral (PI) controller and distributes power based on the state of charge (SOC) and virtual resistance. The third control layer uses the IDBO algorithm to solve the DC microgrid’s optimization model in order to achieve the minimum daily operational cost goal. Simulation results demonstrate that the proposed IDBO algorithm reduces the daily cost in both scenarios by about 14.64% and 9.49% compared to the baseline method. Finally, the feasibility and effectiveness of the proposed hierarchical energy management strategy are verified through experimental results.

To accommodate the growth in the user population and network size in mobile environments, hierarchical architectures of location databases have been proposed. Recent studies showed that the signaling traffic and processing overhead of location updates is expected to grow tremendously, leading to poor performance. The authors present a Profile based Hierarchical location management Scheme (PHS) that focuses on reducing the cost of updates while keeping the lookup cost low. Our proposal is motivated by the observation that users follow repetitive patterns that can be profiled and predicted with reasonable cost, allowing users to send updates occasionally and not on every move. Further, it deploys a simple prediction technique that reduces the uncertainty of a user's location. We quantify the costs and benefits of PHS for several mobility patterns and show that it can result in up to 60% reduction in the update cost with minimal increase (7%) in lookup cost.

This research presents an improved hierarchical key management scheme (IHKMS) with three phase technique for secure group communications in Mobile Ad-hoc Networks (MANETs). It extends two previously proposed models named enhanced hierarchical key agreement scheme (EHKMS) and EHKMS with three phase technique which suffer from two main problems. The first one which exists in both models is that, the main subgroup controller (L1-head) is heavily loaded and has a lot of responsibilities which may lead to its failure. The second problem that exists only in EHKMS is intrusion attacks which may appear in two aspects; frank intrusion and selfish attack. This problem is a fatal one which threatens the security of the system. The proposed IHKMS with three phase technique solves the above mentioned problems. First, it decreases the memory load on the main subgroup header to save its memory resources by distributing a major part of subgroup keys storage into the second level of subgroups headers. Second, it immunizes the IHKMS against intrusions by employing the three phase technique. Applying the three phase technique integrates a certification authentication system in addition to the hierarchal key system used in the IHKMS. The proposed IHKMS with three phase technique enhances EHKMS and EHKMS with three phase technique. It improves the system's reliability in EHKMS, and EHKMS with three phase technique by minimizing the subgroup header's load. Also, it overcomes the intrusion problem that exists only in EHKMS. On the other hand, the complexity of the proposed IHKMS with three phase technique is higher than that of EHKMS. This is anticipated result as the proposed model integrates the three phase technique with the IHKMS.

A hierarchical power management scheme is proposed in this paper for a typical DC Microgrid. Different from other Microgrids, the DC Microgrid can interface to the distribution system by Solid-State transformer (SST). The hierarchical power management strategy includes three control levels: 1) primary control for DC Microgrid to implement distributed operation 2) secondary control for the DC Microgrid bus voltage recovery to achieve seamless mode switch 3) tertiary control to manage the battery charge and discharge. The DC Microgrid can operate in islanding mode, including the individual control for distributed renewable energy source (DRER) and distributed energy storage device (DESD). In addition, the DC microgrid can operate in SST-enabled mode to interface to the distribution system. The DC Micorgrid can seamlessly switch between islanding mode and SST-enable mode. The consideration of state of charge (SOC) for battery is also involved into the tertiary control. To this end, a lab test-bed is constructed to verify the system performance. Lastly, several typical case studies are carried out and the experimental results verify the proposed power management strategy.

Emerging byte-addressable nonvolatile memories (NVMs) promise persistent memory, which allows processors to directly access persistent data in main memory. Yet, persistent memory systems need to guarantee a consistent memory state in the event of power loss or a system crash (i.e., crash consistency). To guarantee crash consistency, most prior works rely on programmers to (1) partition persistent and transient memory data and (2) use specialized software interfaces when updating persistent memory data. As a result, taking advantage of persistent memory requires significant programmer effort, e.g., to implement new programs as well as modify legacy programs. Use cases and adoption of persistent memory can therefore be largely limited. In this paper, we propose a hardware-assisted DRAM+NVM hybrid persistent memory design, Transparent Hybrid NVM (ThyNVM), which supports software-transparent crash consistency of memory data in a hybrid memory system. To efficiently enforce crash consistency, we design a new dual-scheme checkpointing mechanism, which efficiently overlaps checkpointing time with application execution time. The key novelty is to enable checkpointing of data at multiple granularities, cache block or page granularity, in a coordinated manner. This design is based on our insight that there is a tradeoff between the application stall time due to checkpointing and the hardware storage overhead of the metadata for checkpointing, both of which are dictated by the granularity of checkpointed data. To get the best of the tradeoff, our technique adapts the checkpointing granularity to the write locality characteristics of the data and coordinates the management of multiple-granularity updates. Our evaluation across a variety of applications shows that ThyNVM performs within 4.9% of an idealized DRAM-only system that can provide crash consistency at no cost.

In Mobile IP, the signaling traffic overhead will be too high since the new Care-of-Address (CoA) of the mobile node (MN) is registered all the way with the home agent (HA) whenever the MN has moved into a new foreign network. To complement Mobile IP in better handling local movement, several IP micro protocols have been proposed. These protocols introduce a hierarchical mobility management scheme, which divides the mobility into micro mobility and macro mobility according to whether the host's movement is intra-domain or inter-domain. Thus, the requirements on performance and flexibility are achieved, especially for frequently moving hosts. This paper introduces a routing protocol for multicast source mobility on the basis of the hierarchical mobile management scheme, which provides a unified global architecture for both uni- and multicast routing in mobile networks. The implementation of multicast services adopts an improved SSM (Source Specific Multicast) model, which combines the advantages of the existing protocols in scalability and mobility transparency. Simulation results show that the proposed protocol has better performance than the existing routing protocols for SSM source mobility.

A hierarchical energy management strategy for DC microgrid hybrid energy storage systems based on fractional-order sliding mode controller

A simple Voltage-Base Self-Intervention technique is introduced in this paper to perform the switching between the connected distributed generation renewable energy sources. The Voltage-Base Self-Intervention technique fetch maximum power from either the solar photovoltaic or wind energy systems under inhomogeneous climate conditions and output stable voltage for DC -- AC inverter and DC -- DC Boost Converter. In order to fetch the maximum power, the proposed Voltage-Base Self-Intervention technique is composed with the voltage quantification and the increment and decrement hierarchical voltage management and control strategy algorithm. The voltage quantification and the increment and decrement hierarchical voltage management and control strategy algorithm is developed to ensure the DC bus voltage from the solar and wind renewable energy sources can be measured efficiently and effectively during the voltage conduction to perform the Voltage -- Base Self - Intervention. To validate the performances of the proposed Voltage-Base Self-Intervention technique for solar -- wind renewable energy sources, PROTEUS simulations are presented in this paper. Simulation results shows that the proposed technique effectively perform the Voltage -- Base Self -- Intervention between the distributed generations solar -- wind renewable energy sources during the voltage conduction.

Battery/ultracapacitor hybrid energy storage systems have been widely studied in electric vehicles to prolong batteries' cycle life, where the energy management strategy plays a vital role to distribute the load power in real time and to optimize the vehicle economy simultaneously. This paper proposes a hierarchical energy management strategy using sequential quadratic programming and neural network (NN) for a semi-active battery/ultracapacitor hybrid energy storage systems to minimize the battery degradation cost and the electricity cost. In the off-line optimization level, a cost function of battery degradation cost and electricity cost is constructed. Sequential quadratic programming is performed to determine the optimal current reference of ultracapacitors, i.e., the output of the NN. While the load current, velocity, acceleration, the last battery current and ultracapacitor SoC are selected as inputs to train NN until the parameters converge. In the on-line implementation level, the trained NN provides the quasi-optimal reference of ultracapacitor current based on the real-time data. Circuit simulation results on NEDC driving cycle reveal that the proposed strategy can guarantee the ultracapacitor state-of-charge limitations. When compared with the adaptive filter-based method and the near-optimal rule-based method from dynamic programming, a 10.1% and 5.4% reduction of battery degradation and a 9.5% and 3.1% reduction of total cost are achieved by the proposed strategy.

Doubling the number of processing cores on a single processor chip with each technology generation has become conventional wisdom. While future manycore processors promise to offer much increased computational throughput under a given power envelope, sharing critical on-chip resources, such as caches and core- to-core interconnects, poses challenges to guaranteeing predictable performance to an application program. This paper focuses on the problem of sharing on-chip caching capacity among multiple programs scheduled together, especially at the L2 cache level. Specifically, two design aspects of a large shared L2 cache are considered: (1) non-uniform cache access latency and (2) cache contention. We observe that both the aspects have to do with where, among many cache slices, a cache block is mapped to, and present an OS-based approach to managing the on-chip L2 cache memory by carefully mapping data to a cache at the page granularity. We show that a reasonable extension to the OS memory management subsystem and simple architectural support enable enforcing high-level policies to achieve application performance isolation and improve program performance predictability thereof.

As the network grows bigger and faster, the demand for reliable and rapid network monitoring and control is on the increase. For efficient network performance management, the network manager should be able to not only acquire the overall network status information with minimum management traffic, but also immediately figure out the faulty network elements. We propose a hierarchical performance management scheme with operation and maintenance (OAM) management information base (MIB) by using the SNMP management protocol. With this MIB we can remotely monitor each connection and pinpoint the location of a performance problem.

IP mobility can be handled at different layers of the protocol stack. Mobile IP has been developed to handle mobility of Internet hosts at the network layer. As an alternative solution, a number of transport layer mobility protocols have been proposed. However, the location management schemes used in these transport layer solutions are not suitable for frequent mobile handovers due to user's high mobility. In this paper, we propose HiSlGMA, a hierarchical location management scheme for transport layer mobility schemes. We used an analytical model to evaluate HiSlGMA using signaling cost as the performance measure, followed by comparison of the signalling cost of HiSlGMA and hierarchical mobile IPv6 (an enhancement of Mobile IP) and existing transport layer mobility solutions.

Malware and rootkits are serious security threats. They can be designed to be resistant to anti-virus and security software and even remain totally undetectable. This paper describes a hierarchical trust management scheme, where the root of trust is

In the ad hoc networks, group key management is one of the most important secure problems. We propose a hierarchical group key management scheme adapted to large groups according to network characteristics. The scheme put STR hierarchical tree structure into distributed sub-group management model effectively, and combine layer-based key management with cycle-based key management, in order to reduce the communication and computation cost greatly, and is of good attribute in expansibility and lange ad hoc networks.