Conditions For Relaxation Research Articles

Deriving Sufficient Conditions for Exact Relaxation of Complementarity Constraints in Optimization Problems With Energy Storage

Deriving Sufficient Conditions for Exact Relaxation of Complementarity Constraints in Optimization Problems With Energy Storage

Dissipative sliding mode tracking control for discrete-time singular T-S fuzzy systems via a preview target mechanism

This study focuses on the dissipative sliding mode preview tracking control (SMPTC) of discrete-time singular T-S fuzzy systems (STSFSs) via a preview target mechanism. Due to the presence of singular matrix and input matrices with fuzzy rules in the system, the existing preview control approaches cannot be directly adopted. As a result, a novel singular augmented error system (AES) is derived based on a general method. Furthermore, the tracking problem has been translated into the stabilisation of singular AES. A linear sliding mode surface (SMS) is proposed for singular AES, and a suitably SMPTC law is presented. Sufficiency conditions for relaxation are derived to guarantee that the sliding mode dynamics is admissible with the dissipative criterion, and the sliding mode region (SMR) can be reached. The difference singular matrix is fully considered in the whole design process such that the derived conditions can be checked easily. Finally, two examples have shown the effective tracking of the original output signal of system by utilising the proposed SMPTC law.

Approximating Input-Output Curve of Pumped Storage Hydro Plant: A Disjunctive Convex Hull Method

Pumped storage hydro (PSH) plant is a valuable resource with storage and fast ramp capabilities, which can manage the intermittency of renewable energy. An accurate model for the input-output curve of PSH plant can capture its varying efficiency feature and enable accurate evaluations of available generating/pumping capability. However, the trade-off between approximation accuracy and computation time poses a significant challenge for input-output curve modeling. In this paper, we develop a hypograph-relaxation-based input-output curve modeling framework, wherein sufficient conditions for exact hypograph relaxation are defined, proved, and analyzed for fixed-speed PSH considering the value of water in the upper reservoir. Under this framework, a novel disjunctive convex hull model is proposed to balance the aforementioned trade-off. Our model can take advantage of high accuracy in time-consuming piece-wise approximation models, and acceptable computation burden in less-accurate convex hull models. To divide a given input-output curve into various components that can be approximated by their respective convex hulls, we propose to use an approximate convex decomposition (ACD) based approach. The proposed model is tested for profit maximization problems using real-world Ludington PSH station data. Numerical results demonstrated the superior computational advantage of the proposed approach.

An Orthotropic Nonlinear Thermoviscoelastic Model for Polymeric Battery Separators

Structural responses of separators are critical to battery safety. Commonly used separators are dry-processed polymers with anisotropic microstructures. Due to the material anisotropy, rate dependence, and temperature dependence, developing a model for predicting the thermomechanical response of polymeric battery separators has been challenging. This paper presents an orthotropic nonlinear thermoviscoelastic model for predicting the response of polymeric battery separators in thermal ramp scenarios. The model was based on the Schapery nonlinear viscoelastic model and the temperature dependence was introduced through the time-temperature superposition principle (TTSP). The model was implemented in LS-DYNA® finite element (FE) package as a user-defined material model. The model parameters were determined for a polypropylene (PP) separator. The predicted material responses under large deformations in isothermal and non-isothermal temperature conditions for stress relaxation, creep and tensile loadings at different rates agree well with the experimental data.

KKT-based primal-dual exactness conditions for the Shor relaxation

In this work we present some exactness conditions for the Shor relaxation of diagonal (or, more generally, diagonalizable) QCQPs, which extend the conditions introduced in different recent papers about the same topic. It is shown that the Shor relaxation is equivalent to two convex quadratic relaxations. Then, sufficient conditions for the exactness of the relaxations are derived from their KKT systems. It will be shown that, in some cases, by this derivation previous conditions in the literature, which can be viewed as dual conditions, since they only involve the Lagrange multipliers appearing in the KKT systems, can be extended to primal-dual conditions, which also involve the primal variables appearing in the KKT systems.

K-median: exact recovery in the extended stochastic ball model

We study exact recovery conditions for the linear programming relaxation of the k-median problem in the stochastic ball model (SBM). In Awasthi et al. (Relax, no need to round: integrality of clustering formulations. arXiv:1408.4045, 2015; in: Proceedings of the 2015 conference on innovations in theoretical computer science, pp 191–200, 2015), the authors give a tight result for the k-median LP in the SBM, saying that exact recovery can be achieved as long as the balls are pairwise disjoint. We give a counterexample to their result, thereby showing that the k-median LP is not tight in low dimension. Instead, we give a near optimal result showing that the k-median LP in the SBM is tight in high dimension. We also show that, if the probability measure satisfies some concentration assumptions, then the k-median LP in the SBM is tight in every dimension. Furthermore, we propose a new model of data called extended stochastic ball model (ESBM), which significantly generalizes the well-known SBM. We then show that exact recovery can still be achieved in the ESBM.

Conditions for Exact Convex Relaxation and No Spurious Local Optima

Nonconvex optimization problems can be approximately solved via relaxation or local algorithms. For many practical problems such as optimal power flow (OPF) problems, both approaches tend to succeed in the sense that relaxation is usually exact and local algorithms usually converge to a global optimum. In this article, we study conditions that are sufficient or necessary for such nonconvex problems to simultaneously have exact relaxation and no spurious local optima. These conditions help explain the widespread empirical experience that OPF problems, even though computationally hard in theory, seem to be easy in practice.

Utilization of the library recreational function through the Gasibu Library Bandung

Background of the study: One of the capabilities of the library is to provide pleasant conditions for relaxation that cannot be found at home. This research has the background to find out more about the recreational functions of public libraries through the Gasibu Bandung library which is located around the Gasibu field.
 Purpose: The purpose of this study is divided into two parts, namely to determine the recreational function of the library as a means of channeling reading hobbies and to find out the Gasibu library as a tourism developer of Bandung city.
 Method: The technique used in this research is a qualitative research technique with a case study method.
 Findings: The results of this study indicate that the Gasibu library is an appropriate informative recreation facility to serve as a means of channeling people's reading hobbies and the Gasibu library can add to the tourist attraction of Bandung city because of the uniqueness of the information center in the middle of recreational facilities.
 Conclusion: In fulfilling the recreational needs of its users, the Gasibu library is carried out by providing books that are suitable for its purpose. Novels and other literary forms, works of art, travel books, biographies, popular magazines, especially other recreational books. The Gasibu library building is also the main attraction because of its location in the middle of recreational facilities.

Indoor soundscapes at home during the COVID-19 lockdown in London – Part I: Associations between the perception of the acoustic environment, occupantś activity and well-being

Since the outbreak of the COVID-19 pandemic, as a result of the adoption of worldwide lockdown measures, the home environment has become the place where all the daily activities are taking place for many people. In these changed social and acoustical contexts, we wanted to evaluate the perception of the indoor acoustic environment in relation to traditional and new activities performed at home, i.e., relaxation, and working from home (WFH). Taking London as a case study, the present paper presents the results of an online survey administered to 464 home workers in January 2021. The survey utilized a previously developed model for the assessment of indoor soundscapes to describe the affective responses to the acoustic environments in a perceptual space defined by comfort (i.e. how comfortable or annoying the environment was judged) and content (i.e., how saturated the environment is with events and sounds) dimensions. A mixed-method approach was adopted to reinforce result validity by triangulating data from questionnaires and spontaneous descriptions given by participants. In this first part of the study, the main objectives were: (1) evaluating differences in soundscape evaluation, in terms of comfort and content dimensions, based on the activity performed at home, (2) identifying appropriate conditions for WFH and relaxation, and (3) investigating associations between psychological well-being and indoor soundscapes. The results showed that the environments were perceived as more comfortable and slightly fuller of content when rated in relation to relaxation than for WFH, thus suggesting a stricter evaluation of the acoustic environment in the latter case. As regards the second objective, spaces that were more appropriate for relaxation had high comfort, whereas spaces appropriate for WFH resulted more private and under control, i.e. with high comfort and low content scores. Lastly, better psychological well-being was associated with more comfortable soundscapes, both for WFH (rs = 0.346, p < .0005), and relaxation (rs = 0.353, p < .0005), and with lower content while WFH (rs = −0.133, p = .004). The discussion points out the need of considering the implications of changed working patterns to rethink the design of soundscapes in residential buildings, also in relation to potential well-being outcomes that will be further investigated in the Part II of the study.

EMOTIONAL PROBLEMS AND SLEEP DISTURBANCES IN PARAMEDICS IN THE ERA OF THE COVID-19 PANDEMIC

Infectious diseases have accompanied mankind for centuries, and the effects of their dramatic course are felt on many levels of everyday life. The COVID-19 pandemic caused by SARS-CoV-2 virus infection carries a tremendous psychological burden for both those infected and health care workers. Particularly vulnerable to psychological strain are paramedics who have direct contact with and caring for patients infected with coronavirus. From a review of the literature, it is known that Emergency Medical Team members, as a result of the stress experienced during a pandemic, manifest symptoms such as depression, anxiety, and sleep disturbances. In order to limit the adverse impact of the pandemic on the mental condition of this professional group, it is necessary to create appropriate conditions for solitary rest, relaxation and satisfaction of basic needs such as: food, sleep and protective clothing. An important role is also played by unrestricted access to psychological support in the broad sense of the word and often also to psychiatric care.

Hypothesis about physical-chemical nature of gas-dynamic phenomena in coal mines

Practical experience in the development of a gas-saturated coal-rock massif, as well as the results of scientific research, point to the imperfection of the existing ideas regarding the processes in the extremely stressed coal-rock massif, mechanisms of the occurrence and behavior of gas-dynamic phenomena (GDP). The conducted analysis for the problem state regarding the nature and mechanism of sudden outbursts of coal, rocks and gas, in general, confirm that the outburst hazard was due to the complex interaction of three main natural factors (stress state, gas factor and physical-mechanical properties of rocks) with technological ones, and the formation of outburst hazardous conditions occurs in geological environments that are characterized by certain properties and conditions. The purpose of the paper is to obtain new theoretical understanding of the GDP nature with taking into account geological conditions and the impact of external factors by developing a hypothesis regarding the physicochemical nature of the GDP. It is proved that relief of stresses arisen in the molecular structure under the impact of geological factors leads to the activation of relaxation processes in the substance. The relaxation of the accumulated energy system results in structural transformations with the release of low-molecular-weight compounds. According to this pattern, accumulation of gases genetically connected with fossil organic matter and the emergence of gas-dynamic phenomena.is formed in the coal-rock massif. The key point of the hypothesis is that partial stress relief of the coal-rock massif creates in the fractured zones of the coal bed conditions for relaxation of elastic energy accumulated in the molecular structure of coal, hence, promoting the activation of structural transformations by the free-radical mechanism, which results in the release of low-molecular-weight compounds (methane, in particular). Under appropriate conditions, in the zone of relaxation of elastic deformations, the process can assume an avalanche character, namely, initiate sudden outbursts of coal and gas. According to the physicochemical model of methane release in coal under the impact of geomechanical, geological, and technogenic factors, which is proposed within the framework of this work, partial discharge creates in the coal bed conditions for relaxation of the elastic energy accumulated in the molecular structure of coal. That is, it promotes the activation of structural transformations by the free-radical mechanism, the result of which is the release of low-molecular-weight compounds (methane). Under the condition of sufficiently high fracturing of the elastic deformation zone, the process acquires an avalanche character, that is, sudden outbursts of coal and gas are developed. Keywords: coal, coal mines, gas-dynamic phenomena, outbursts of coal and gas, stress-strain state.

Characterization of Hazy Morphology on AlInP/GaAs Epitaxial Wafers Grown by Organometallic Vapor Phase Epitaxy

6-inch AlInP/GaAs epitaxial wafers grown by organometallic vapor phase epitaxy (OMVPE) technique are being developed for light emitting diodes (LEDs) applications [1]. Recently, dislocation configurations in the GaAs substrates and AlInP epilayers have been characterized and conditions for relaxation and formation of misfit dislocations were analyzed [2,3]. Apart from defects such as dislocations, epilayer surface reveals a hazy morphology formed when the epitaxial growth pressure is increased. It is observed that the epilayer surface is rougher compared to regular clear regions as revealed by both optical microscopy and atomic force microscopy. Additionally, the size of the hazy regions increases with growth pressure but other growth parameters such as growth temperature, V/III ratio, likely influence the onset of hazy morphology. Previous research on the formation of hazy features reports that these can be caused by the deficiency of phosphorus [4], lowered V/III ratio [5] or stacking faults [6]. However, the hazy features in our case, are different from the ones reported. Synchrotron X-ray topographs of the hazy regions showed blurred contrast, indicating disordered lattice arrangement. Moreover, internal structure of the hazy regions was studied by reciprocal space mapping (RSM), where weakened and broadened peaks around the clear epilayer peak were observed using 004 reflection, indicating continuously varying strain and tilt between the hazy region and the clear region. The thickness of the hazy regions was also analyzed by employing the 002 RSM, where the X-ray penetration depth is lower. Comparison of the 002 and 004 RSMs reveals that at the beginning of epitaxial growth, the epilayers do not suffer from lattice distortion and the formation of the hazy morphology occurs when a critical thickness is exceeded.Reference:[1] C. H. Chen, S. A. Stockman, M. J. Peanasky, C. P. Kuo. Brightness Light Emitting Diodes Semiconductors and Semimetals, SEMICONDUCT SEMIMET, 48 (1997) pp. 97–144[2] Hongyu Peng, Tuerxun Ailihumaer, Yafei Liu, Balaji Raghothamachar and Michael Dudley, J. Cryst. Growth, 533 (2020) 125458[3] Hongyu Peng, Tuerxun Ailihumaer, Balaji Raghothamachar and Michael Dudley, J. Electron. Mater. 49, 3472–3480 (2020)[4] H. H. Ryu, M. H. Jeon, J. Y. Leem, H. J. Song, L. P. Sadwick, G. B. Stringfellow, J Mater Sci (2006) 41:8265–8270[5] D. S. Cao and G. B. Stringfellow, Journal of Electronic Materials, Vol. 20, No. 1, 1991[6] Yoshihiro Hiraya, Fumiya Ishizaka, Katsuhiro Tomioka and Takashi Fukui, Applied Physics Express 9, 035502 (2016) Figure 1

Generalized Einstein relations and conditions for anomalous relaxation.

The generalized Einstein relation (GER) for nonergodic processes is investigated within the framework of the generalized Langevin equation. The conditions for anomalous relaxation such as long-tail decay and non-vanishing velocity autocorrelation function (VAF) are proposed and distinguished. For the stationary nonergodic process, if the initial preparation of the particle velocity is non-thermal, an asymptotic GER occurs in a departure from the usual result. It is shown that the GER holding is a necessary condition rather than a full condition for the system being close to equilibrium. For the nonergodic process of the second type due to cutoff of high frequencies, the VAF oscillates with time, the GER holds but the equilibrium fails in the long-time limit. Applications to some practical examples confirm the present theoretical findings.

Construction and validation of the Adult Stressors Inventory (ASI).

A great deal of research has been conducted all over the world into stress and its impacts on the health of populations. To develop and validate an instrument for identification of the principal stressors and their magnitude in people who are subject to stress. The instrument was constructed on the basis of analysis of 20 interviews conducted with 10 male and 10 female adults with stress according to the Perceived Stress Scale. A total of 46 statements were derived from this analysis, referring to stressful situations in different areas of life. Each statement is evaluated on a Likert response scale indicating the degree of impact and the respondent's ability to deal with the stressor it describes. The instrument was validated with a non-probabilistic sample comprised 450 adults, aged from 18 to 65 years, 62.7% women and 37.3% men, who completed the instrument and also the Perceived Stress Scale, to enable criterion validation. Exploratory factor analysis identified 42 valid items and grouped them into eight factors that explained 64.5% of total variance. These factors were financial stressors; working environment stressors; cognitive and behavioral stressors; family environment stressors; health status stressors; stressors related to conditions for relaxation; workload-related stressors; and social relationship stressors. Cronbach's alpha for the instrument was 0.94. A relationship was observed between the newly-developed inventory and the Perceived Stress Scale, providing grounds for accepting the validation hypothesis. The results were psychometrically satisfactory and made possible provision of a new instrument for stress interventions, with advantages over other instruments.

Comparison of intubation condition and the quality of muscle relaxation between rocuronium and vecuronium using "timing principle".

Aim To compare the quality of the conditions for endotracheal intubation and muscle relaxation between rocuronium bromide and vecuronium bromide using the ''timing principle'' method for induction in anaesthesia. The "timing principle" includes the administration of muscle relaxants before the hypnotic agent during induction in anaesthesia. Method Sixty patients who had undergone elective surgery were randomly allocated into two equal groups using muscle relaxants: rocuronium (group R) and vecuronium (group V). The intubation conditions were assessed using Cooper's scoring system, based on jaw relaxation, vocal cords position and response to intubation. The quality of muscle relaxation was evaluated by recording the time of clinical weakness, a count of ''train of four'' (TOF) twitches at intubation, the time of loss TOF response and duration of direct laryngoscopy. Results The intubation conditions were excellent in 100% of patients in the group R versus excellent in 80% and good in 20% of patients in the group V (p<0.05). The time of clinical weakness was statistically significantly shorter in the group R than in the group V (p<0.000). The time of loss of TOF response was statistically significantly shorter in the group R (p<0.000). The absence of TOF twitches (the level of muscle relaxation of 100%) at intubation recorded in 25 (83.3%) patients in the group R versus five (16.7%) patients in the group V (p<0.000). Duration of direct laryngoscopy did not significantly differ between the groups. Conclusion Rocuronium bromide provides better intubation conditions and greater quality of muscle relaxation than vecuronium bromide using ''timing principle'' technique.

Circular loops of misfit dislocations in decahedral core-shell nanoparticles

A theoretical model is proposed for stress relaxation in decahedral core-shell nanoparticles through formation of circular prismatic misfit dislocation loops at the core-shell interface. The critical conditions for stress relaxation are determined and discussed in comparison with those for single-crystalline core-shell nanoparticles. It is shown that decahedral core-shell nanoparticles should be less stable with respect to misfit dislocation generation than single-crystalline ones when the lattice parameter of the core is larger than that of the shell. Theoretical results are compared with experimental observations available in the literature and are shown to be in a good agreement with the latter.

Extended sufficient conditions for exact relaxation of the complementarity constraints in storage-concerned economic dispatch

Storage is widely considered in economic dispatch (ED) problems. To prevent simultaneous charging and discharging of a storage device, a storage-concerned ED problem should involve complementarity constraints for every storage device to make the problem strongly non-convex. In this case, the conventional Karush-Kuhn-Tucker optimality conditions are unsuitable, and the methods that are normally effective are also invalid. In our recent paper, we proposed a new exact relaxation method that directly removes the complementarity constraints from a storage-concerned ED model to make it convex and easy to solve. This paper extends the previous study by presenting and analyzing two new groups of sufficient conditions that guarantee exact relaxation. Different application conditions of these groups of sufficient conditions are discussed. Numerical tests are performed to show the benefit of using the exact relaxation method and the different suitable application conditions of these groups of sufficient conditions. This paper contributes to a wide application of exact relaxation in storage-concerned ED problems.

Wealth and sensibility. The historical outcome of better living conditions for all according to Adam Smith

ABSTRACTIn this paper, I argue that Smith's commercial society is characterised more by restraint of self-command than by restraint of emotions through self-command, as usually stated. According to Smith, the appropriate degree of self-command varies with historical circumstances: better living conditions for all favour relaxation of self-command and lead people to express their sentiments more freely. I thus highlight a crucial link in Smith's thought between variations in general economic conditions and variations in moral judgement on the expression of emotions, or, in other words, between The Theory of Moral Sentiments and the Wealth of Nations.

Связь характеристик образовательной среды детского сада и уровня развития регуляторных функций дошкольников

This paper presents an empirical study on the interrelationship between levels of regulatory functions development in preschool children and the quality of preschool education.The study involved 31 groups of preschool children in Moscow (657 children aged 5—6 years).ECERS-R scales and the NEPSY-II battery were used.A number of significant correlations was revealed between such components of regulatory functions as verbal working memory, visual-spatial working memory, inhibitory control, cognitive flexibility and various environmental factors.The paper stresses the importance of creating conditions for recreation and relaxation as well as for the development of gross motor skills, and highlights the significance of group interaction for the development of regulatory functions in children.

(Invited) Fabrication of AlGaN/InGaN/GaN Quantum Wires for Electronic and Optoelectronic Applications

AlGaInN epi structures are used for manufacturing white LEDs, UV, blue and green laser diodes (LD) and high-power/high-frequency transistors. In this work, we will show our proprietary and patented technology of lateral patterning in which we fabricate GaN substrates with locally variable off-cut (variable atomic step width). Such substrates are used for InGaN and AlGaN growth of 3-dimensional epi structures. The GaN off-cut influences a number of AlGaInN characteristics: Indium incorporation (smaller for a higher off-cut), Ga and N vacancies concentration, critical conditions for relaxation, decomposition rate, and some others. Therefore, using the GaN substrates after such lateral patterning, we may fabricate nano-wires which would be used for electronic device manufacturing. Unfortunately, AlGaInN epitaxial layers contain a large number of defects (dislocations, trench defects, In-clusters, and some others) which disturb the step-flow. We will show a comparison of results obtained using different GaN crystals: thick layers on sapphire and SiC (dislocation density higher than 108 cm-2), bulk crystals grown by various methods having dislocation density between 107 cm-2 and 104 cm-2. Then, we will present how the growth conditions (temperature, pressure, flows of reactants, presence of hydrogen in the carrier gas) influence the nanowire formation. One of the big issues in nitride technology is InGaN decomposition during the p-type growth at temperatures higher than those used for InGaN growth. Therefore, part of the presentation will be devoted to that issue, in particular, how lateral patterning may influence this decomposition.