Distributed Coupled Multi-Agent Stochastic Optimization

This work develops effective distributed strategies for the solution of constrained multi-agent stochastic optimization problems with coupled parameters across the agents. In this formulation, each agent is influenced by only a subset of the entries of a global parameter vector or model, and is subject to convex constraints that are only known locally. Problems of this type arise in several applications, most notably in disease propagation models, minimum-cost flow problems, distributed control formulations, and distributed power system monitoring. This work focuses on stochastic settings, where a stochastic risk function is associated with each agent and the objective is to seek the minimizer of the aggregate sum of all risks subject to a set of constraints. Agents are not aware of the statistical distribution of the data and, therefore, can only rely on stochastic approximations in their learning strategies. We derive an effective distributed learning strategy that is able to track drifts in the underlying parameter model. A detailed performance and stability analysis is carried out showing that the resulting coupled diffusion strategy converges at a linear rate to an $O(\mu)-$neighborhood of the true penalized optimizer

Linear Convergence of Primal-Dual Gradient Methods and their Performance in Distributed Optimization

In this work, we revisit a classical incremental implementation of the primal-descent dual-ascent gradient method used for the solution of equality constrained optimization problems. We provide a short proof that establishes the linear (exponential) convergence of the algorithm for smooth strongly-convex cost functions and study its relation to the non-incremental implementation. We also study the effect of the augmented Lagrangian penalty term on the performance of distributed optimization algorithms for the minimization of aggregate cost functions over multi-agent networks

Characterization of Saturn's bow shock: magnetic field observations of quasi-perpendicular shocks

Collisionless shocks vary drastically from terrestrial to astrophysical regimes resulting in radically different characteristics. This poses two complexities. First, separating the influences of these parameters on physical mechanisms such as energy dissipation. Second, correlating observations of shock waves over a wide range of each parameter, enough to span across different regimes. Investigating the latter has been restricted since the majority of studies on shocks at exotic regimes (such as supernova remnants) have been achieved either remotely or via simulations, but rarely by means of in situ observations. Here we present the parameter space of MA bow shock crossings from 2004 to 2014 as observed by the Cassini spacecraft. We find that Saturn's bow shock exhibits characteristics akin to both terrestrial and astrophysical regimes (MA of order 100), which is principally controlled by the upstream magnetic field strength. Moreover, we determined the θBn of each crossing to show that Saturn's (dayside) bow shock is predominantly quasi-perpendicular by virtue of the Parker spiral at 10 AU. Our results suggest a strong dependence on MA in controlling the onset of physical mechanisms in collisionless shocks, particularly nontime stationarity and variability. We anticipate that our comprehensive assessment will yield deeper insight into high MA collisionless shocks and provide a broader scope for understanding the structures and mechanisms of collisionless shocks

Haptic Experience and the Design of Drawing Interfaces

Haptic feedback has the potential to enhance users’ sense of being engaged and creative in their artwork. Current work on providing haptic feedback in computer-based drawing applications has focused mainly on the realism of the haptic sensation rather than the users’ experience of that sensation in the context of their creative work. We present a study that focuses on user experience of three haptic drawing interfaces. These interfaces were based on two different haptic metaphors, one of which mimicked familiar drawing tools (such as pen, pencil or crayon on smooth or rough paper) and the other of which drew on abstract descriptors of haptic experience (roughness, stickiness, scratchiness and smoothness). It was found that users valued having control over the haptic sensation; that each metaphor was preferred by approximately half of the participants; and that the real world metaphor interface was considered more helpful than the abstract one, whereas the abstract interface was considered to better support creativity. This suggests that future interfaces for artistic work should have user-modifiable interaction styles for controlling the haptic sensation

Improvement of speed response in four-phase DC–DC converter switching using two shunt voltage-source

This study proposes a technique that is able to improve the speed response of a four-phase DC–DC converter switching. The basic concept of the proposed technique is the inclusion of two shunt-connected voltage sources in series to the converter system. Using a higher input voltage to drive the load, a higher current per microsecond output system will be obtained and reverts to its nominal input upon obtaining desired references. Thus, the transient response observed when using this proposed technique is found to be much faster when compared to the conventional converter. Moreover, this technique is easily implemented as it requires only an additional voltage source, power switch, and power diode. The integrated model of the two shunt voltage-source in a four-phase DC–DC converter was simulated in MATLAB/Simulink and validated against the experimental results of a laboratory prototype, 600 W four-phase DC–DC converter. The novelty of this proposed technique is its ability to provide faster operations for critical loads applications, lower output capacitor and lower operating frequency

Self-machinery?: steel trusses and the management of ruptures in eighteenth-century Europe

Abstract: Effectiveness Of Rice Husk Ash And Poly Aluminum Chloride In Reducing Exposure Colour Liquid Waste Industry Sasirangan. Sasirangan fabric industry is the textile of industry in Kalimantan Selatan produce wastewater of dyeing cloth sasirangan process that uses water as a primary adjuvant in stage process.The study aims to determine the effectiveness of rice husk ash and Poly Aluminium Chloridereduce levels of dyes in wastewater sasirangan "Oriens Handycraft". This study tested a laboratory scale with dose variation of rice husk ash and Poly Aluminium Chloride for reduced levels of dyes in wastewater sasirangan. The study design is a randomized pretest - posttest control group design. The population of the waste liquid fabric manufacturesasirangan results and samples are the waste from the manufacture of cloth sasirangan which represents the population. This study conduct statistical tests usingKruskal Wallis and Mann-Whitney Test.Theresultsofthestudyof color levels priorto treatment equal to 2,712 PtCo and after treatment ranges from 676.3 to 978.7 PtCo at a dose of 58 grams of rice husk ash; 59 g; 60 g; 61 g; 62 gr and Poly Aluminium Chloride 0.5 gr. For a dose of 58 grams of rice husk ash; 59 g; 60 g; 61 g; 62 gr and Poly Aluminium Chloride 1 g of color levels before treatment and after PtCo 1775 amounted to 227.7 PtCo ranges up to 240 PtCo. Rice husk ash and Poly Aluminium Chloride effective at pH 6.5 - 7. Results of normality test showed abnormal data. Kruskal Wallis test probability value 0.002 <0.05, there is a difference between the average dosing in the control group and the treatment group and the Mann-Whitney Test probability value of 0.009 (0.018 <0.05), the rice husk ash dosing and Poly Aluminium Chloride 1 g more effective than rice husk ash dosing and Poly Aluminium Chloride 0.5 g.Efforts government can do is provide the appropriate policy on effluent quality standards and attention to industrial waste disposal sasirangan. For the industry can manage its waste before waste into the environment. Keywords: SasiranganWaste; Materials coagulant; pH; Dye