On-demand Mechanism Research Articles

A Distributed Particle-Swarm-Optimization-Based Fuzzy Clustering Protocol for Wireless Sensor Networks.

Clustering is considered to be one of the most effective ways for energy preservation and lifetime maximization in wireless sensor networks (WSNs) because the sensor nodes are equipped with limited energy. Thus, energy efficiency and energy balance have always been the main challenges faced by clustering approaches. To overcome these, a distributed particle swarm optimization-based fuzzy clustering protocol called DPFCP is proposed in this paper to reduce and balance energy consumption, to thereby extend the network lifetime as long as possible. To this end, in DPFCP cluster heads (CHs) are nominated by a Mamdani fuzzy logic system with descriptors' residual energy, node degree, distance to the base station (BS), and distance to the centroid. Moreover, a particle swarm optimization (PSO) algorithm is applied to optimize the fuzzy rules, instead of conventional manual design. Thus, the best nodes are ensured to be selected as CHs for energy reduction. Once the CHs are selected, distance to the CH, residual energy, and deviation in the CH's number of members are considered for the non-CH joining cluster in order to form energy-balanced clusters. Finally, an on-demand mechanism, instead of periodic re-clustering, is utilized to maintain clusters locally and globally based on local information, so as to further reduce computation and message overheads, thereby saving energy consumption. Compared with the existing relevant protocols, the performance of DPFCP was verified by extensive simulation experiments. The results show that, on average, DPFCP improves energy consumption by 38.20%, 15.85%, 21.15%, and 13.06% compared to LEACH, LEACH-SF, FLS-PSO, and KM-PSO, and increases network lifetime by 46.19%, 20.69%, 20.44%, and 10.99% compared to LEACH, LEACH-SF, FLS-PSO, and KM-PSO, respectively. Moreover, the standard deviation of the residual network was reduced by 61.88%, 55.36%, 54.02%, and 19.39% compared to LEACH, LEACH-SF, FLS-PSO, and KM-PSO. It is thus clear that the proposed DPFCP protocol efficiently balances energy consumption to improve the overall network performance and maximize the network lifetime.

Deep Eutectic Solvent-Enabled Plasmonic Nanocellulose Aerogel: On-Demand Three-Dimensional (3D) SERS Hotspot Based on Collapsing Mechanism.

Exceptional surface enhanced Raman scattering (SERS) can be achieved by on-demand mechanisms mediated by the formation of three-dimensional (3D) network supporting hotspots. Herein, a deep eutectic solvent (DES) is used to fabricate plasmonic aerogels as sustainable SERS substrates consisting of different gold nanoparticle (AuNP) heterostructures synthesized in the presence of cellulose nanocrystals (CNCs). This analytical approach is based on the AuNPs 3D arrangement within the CNC matrix, where the transient inter-CNCs interactions collapse after loading with the analyte aqueous solution, forming hotspots on demand. Theoretical calculations support the on-demand SERS mechanism, which consists of the hotspot formation by bringing the AuNPs closer upon activation with the liquid sample loading. To evaluate the plasmonic aerogel performance as a sensing platform, the organophosphorus pesticides edifenphos and parathion were tested in rice and tea extracts. Also, the detection of Methylene Blue in fish muscle extract resulted in a detection limit of 9.8 nM. The results demonstrate that the 3D plasmonic aerogel exhibits significantly higher SERS enhancement and sensitivity when compared to conventional 2D SERS substrates. The use of a green designer solvent, biobased ingredients, and the introduction of on-demand SERS-based sensing pave the way for further developments in the analysis of liquid samples within a sustainable framework.

A Healable Resistive Heater as a Stimuli-Providing System in Self-Healing Soft Robots

Self-healing polymers can address the damage susceptibility in soft robotics. However, in most cases, their healing requires a heat stimulus, provided by an external device. This letter presents a self-healing soft actuator with an integrated healable flexible heater, functioning as the stimuli-providing system. The actuator is constructed out of thermoreversible elastomers that are crosslinked by the Diels-Alder (DA) reaction, which provides the healing ability. The heater is manufactured from a DA-based composite network filled with 20 wt% carbon black to provide electrically conductive properties for resistive Joule heating. The flexibility of the heater does not compromise the actuator performance upon integration and the self-healing properties of both heater and actuator allow for damage repair. This includes very large damages, as both heater and actuator can recover (near 100%) from being cut completely in two pieces, using Joule heating at 90°C with a bias voltage of about 30 V. The embedded heater avoids the need for external intervention in the healing process, and provides healing quality assessment and a healing on-demand mechanism, paving the way for an optimum healing solution of damage resilient soft robots that require heat as a healing stimulus.

Virtual machine placement mechanisms in the cloud environments: a systematic review

PurposeVirtual machines (VMs) are suggested by the providers of cloud services as the services for the users over the internet. The consolidation of VM is the tactic of the competent and smart utilization of resources from cloud data centers. Placement of a VM is one of the significant issues in cloud computing (CC). Physical machines in a cloud environment are aware of the way of the VM placement (VMP) as the mapping VMs. The basic target of placement of VM issue is to reduce the physical machines' items that are running or the hosts in cloud data centers. The VMP methods have an important role in the CC. However, there is no systematic and complete way to discuss and analyze the algorithms. The purpose of this paper is to present a systematic survey of VMP techniques. Also, the benefits and weaknesses connected with selected VMP techniques have been debated, and the significant issues of these techniques are addressed to develop the more efficient VMP technique for the future.Design/methodology/approachBecause of the importance of VMP in the cloud environments, in this paper, the articles and important mechanisms in this domain have been investigated systematically. The VMP mechanisms have been categorized into two major groups, including static and dynamic mechanisms.FindingsThe results have indicated that an appropriate VMP has the capacity to decrease the resource consumption rate, energy consumption and carbon emission rate. VMP approaches in computing environment still need improvements in terms of reducing related overhead, consolidation of the cloud environment to become an extremely on-demand mechanism, balancing the load between physical machines, power consumption and refining performance.Research limitations/implicationsThis study aimed to be comprehensive, but there were some limitations. Some perfect work may be eliminated because of applying some filters to choose the original articles. Surveying all the papers on the topic of VMP is impossible, too. Nevertheless, the authors are trying to present a complete survey over the VMP.Practical implicationsThe consequences of this research will be valuable for academicians, and it can provide good ideas for future research in this domain. By providing comparative information and analyzing the contemporary developments in this area, this research will directly support academics and working professionals for better knowing the growth in the VMP area.Originality/valueThe gathered information in this paper helps to inform the researchers with the state of the art in the VMP area. Totally, the VMP's principal intention, current challenges, open issues, strategies and mechanisms in cloud systems are summarized by explaining the answers.

Data-Driven Auction Mechanism Design in IaaS Cloud Computing

With the emergence of big data computing and analysis, cloud computing services become more and more popular, which has recently drawn researchers’ great attentions to develop various new applications and mechanisms. In this paper, we consider the on-demand mechanism design in the infrastructure as a service (IaaS), including resource allocation and pricing issues under dynamic scenarios. Most of existing works on mechanism design assumed static and independent individual utility, while the cloud computing services are provided in a dynamic environment. To solve such problems, we start with analyzing the Google cluster-usage dataset to draw the statistical and stochastic characteristics of the IaaS consumers and providers. Based on the characteristics mined from real data, we propose a stochastic matching algorithm with Markov Decision Process (MDP), which aims at optimizing the long-term system efficiency, with its online version using Q-learning method to address the imperfect model estimation problem. We further design an efficient (EF), incentive compatible (IC), individual rational (IR) auction mechanism, which is an extension of traditional Vickrey-Clarke-Groves (VCG) mechanism. The proposed mechanism is studied under two application scenario: quality sensitive services, where unilateral MDP-VCG auction is implemented; and quality insensitive services, where MDP-VCG double auction is implemented. To verify the performance of our proposed mechanism, we conduct experiment using the Google dataset and show that the proposed MDP-based VCG auction mechanism can achieve EF, IC and IR properties simultaneously.

On-demand erythrocyte disposal and iron recycling requires transient macrophages in the liver.

Iron is an essential component of the erythrocyte protein hemoglobin and is crucial to oxygen transport in vertebrates. In the steady state, erythrocyte production is in equilibrium with erythrocyte removal1. In various pathophysiological conditions, however, erythrocyte life span is severely compromised, which threatens the organism with anemia and iron toxicity2,3. Here we identify an on-demand mechanism that clears erythrocytes and recycles iron. We show that Ly-6Chigh monocytes ingest stressed and senescent erythrocytes, accumulate in the liver via coordinated chemotactic cues, and differentiate to ferroportin 1 (FPN1)-expressing macrophages that can deliver iron to hepatocytes. Monocyte-derived FPN1+ Tim-4neg macrophages are transient, reside alongside embryonically-derived Tim-4high Kupffer cells, and depend on Csf1 and Nrf2. The spleen likewise recruits iron-loaded Ly-6Chigh monocytes, but these do not differentiate into iron-recycling macrophages due to the suppressive action of Csf2. Inhibiting monocyte recruitment to the liver leads to kidney and liver damage. These observations identify the liver as the primary organ supporting rapid erythrocyte removal and iron recycling and uncover a mechanism by which the body adapts to fluctuations in erythrocyte integrity.

A molecular mechanism to regulate lysosome motility for lysosome positioning and tubulation.

To mediate the degradation of bio-macromolecules, lysosomes must traffic towards cargo-carrying vesicles for subsequent membrane fusion or fission. Mutations of the lysosomal Ca2+ channel TRPML1 cause lysosome storage disease (LSD) characterized by disordered lysosomal membrane trafficking in cells. Here we show that TRPML1 activity is required to promote Ca2+-dependent centripetal movement of lysosomes towards the perinuclear region, where autophagosomes accumulate, upon autophagy induction. ALG-2, an EF-hand-containing protein, serves as a lysosomal Ca2+ sensor that associates physically with the minus-end directed dynactin-dynein motor, while PI(3,5)P2, a lysosome-localized phosphoinositide, acts upstream of TRPML1. Furthermore, the PI(3,5)P2-TRPML1-ALG-2-dynein signaling is necessary for lysosome tubulation and reformation. In contrast, the TRPML1 pathway is not required for the perinuclear accumulation of lysosomes observed in many LSDs, which is instead likely caused by secondary cholesterol accumulation that constitutively activates Rab7-RILP-dependent retrograde transport. Collectively, Ca2+ release from lysosomes provides an on-demand mechanism regulating lysosome motility, positioning, and tubulation.

Contributory provision point contracts – a risk-free mechanism for hedging cloud energy costs

Cloud computing services rely on electricity to power compute-servers, network equipment, cooling systems, and other supporting infrastructure. As such, energy costs are a substantial outgoing to public providers of cloud computing services. On-demand pricing, where consumers are not required to give advance notice of requirements, does not aid the provider in planning future demand, and therefore makes it more difficult to purchase energy at discounted rates. In this paper, we propose an advance pricing mechanism for cloud computing resources based on provision-point contracts, commonly used by deal-of-the-day websites such as Groupon. We show how our Contributory Provision Point (CPP) contracts reward consumers with reduced prices for advance reservations, while allowing providers to make accurate forecasts of energy usage. We show how CPP contracts are risk-free for the provider, guaranteeing to be at least as profitable as on-demand mechanisms where electricity is purchased ad-hoc by the provider. Through a computer simulation, we demonstrate that CPP contracts can be more profitable for the provider compared to a traditional method of hedging electricity futures using a popular forecasting algorithm. Furthermore, we show that CPP contracts encourage consumers to forecast honestly by rewarding them with discounted rates, while remaining profitable for the provider, even when forecasts are not completely accurate.

An Integrated Framework for Dependable and Revivable Architectures Using Multicore Processors

This paper presents a high-availability system architecture called INDRA an INtegrated framework for Dependable and Revivable Architecture that enhances a multicore processor (or CMP) with novel security and fault recovery mechanisms. INDRA represents the first effort to create remote attack immune, self-healing network services using the emerging multicore processors. By exploring the property of a tightly-coupled multicore system, INDRA pioneers several concepts. It creates a hardware insulation, establishes finegrained fault monitoring, exploits monitoring/backup concurrency, and facilitates fast recovery services with minimal performance impact. In addition, INDRA's fault/exploit monitoring is implemented in software rather than in hardware logic, thereby providing better flexibility and upgradability. To provide efficient service recovery and thus improve service availability, we propose a novel delta state backup and recovery on-demand mechanism in INDRA that substantially outperforms conventional checkpointing schemes. We demonstrate and evaluate INDRA's capability and performance using real network services and a cycle-level architecture simulator. As indicated by our performance results, INDRA is highly effective in establishing a more dependable system with high service availability using emerging multicore processors.

Functional closure of the femoral canal revealed by computed tomographic scanning.

The lacuna vasorum contains, as well as the external iliac vessels, a space called the femoral canal which allows pulsation and other changes in the diameter of the two vessels. The canal is closed by a connective tissue septum which is too weak to prevent a herniation alongside the vessels. The functional closure of the canal was investigated by artificial augmentation of the intraluminal pressure of the vein in five specimens and by computed tomographic (CT) scanning during a Valsalva manoeuvre in ten normal persons. In the abdomen the intraluminal and extraluminal pressures are raised in parallel, with no consequence for the diameter of the vessels. In the area of the lacuna vasorum the intravenous pressure is conveyed down to the first competent valve which is located 0.5 cm distal to the inguinal ligament, while the extraluminal pressure is reduced to normal. At each rise of the intra-abdominal pressure the vein will therefore bulge and exactly fill the empty space of the femoral canal thus preventing herniations by an on-demand mechanism. By CT scanning it was found that the vein in the femoral canal increased its diameter 2.5-3.0 times during the Valsalva manoeuvre.