Exploiting Soft Constraints within Decomposition and Coordination Methods for Sub-hourly Unit Commitment

Unit commitment (UC) is an important problem solved on a daily basis within a strict time limit. While hourly UC problems are currently considered, they may not be flexible enough with the fast-changing demand and the increased penetration of intermittent renewables. Sub-hourly UC is therefore recommended. This, however, will significantly increase problem complexity even under the deterministic setting, and current methods may not be able to obtain good solutions within the time limit. In this paper, deterministic sub-hourly UC is considered, with the innovative exploitation of soft constraints – constraints that do not need to be strictly satisfied, but with predetermined penalty coefficients for their violations. The key idea is the “surrogate optimization” concept that ensures multiplier convergence within “surrogate” Lagrangian relaxation as long as the “surrogate optimality condition” is satisfied without the need to optimally solve the “relaxed problem.” Consequently, subproblems can still be formed and optimized when soft constraints are not relaxed, leading to a drastically reduced number of multipliers and improved performance. To further enhance the method, a parallel version is developed. Testing results on the Polish system demonstrate the effectiveness and robustness of both the sequential and parallel versions at finding high-quality solutions within the time limit.

Download Full-text

Exploiting Soft Constraints within Decomposition and Coordination Methods for Sub-hourly Unit Commitment

10.36227/techrxiv.12950414 ◽

2020 ◽

Author(s):

Niranjan Raghunathan ◽

Mikhail Bragin ◽

Bing Yan ◽

Peter Luh ◽

Khosrow Moslehi ◽

...

Keyword(s):

Unit Commitment ◽

Daily Basis ◽

Time Limit ◽

Soft Constraints ◽

Problem Complexity ◽

Surrogate Optimization ◽

Parallel Version ◽

Improved Performance ◽

Coordination Methods ◽

Relaxed Problem

Unit commitment (UC) is an important problem solved on a daily basis within a strict time limit. While hourly UC problems are currently considered, they may not be flexible enough with the fast-changing demand and the increased penetration of intermittent renewables. Sub-hourly UC is therefore recommended. This, however, will significantly increase problem complexity even under the deterministic setting, and current methods may not be able to obtain good solutions within the time limit. In this paper, deterministic sub-hourly UC is considered, with the innovative exploitation of soft constraints – constraints that do not need to be strictly satisfied, but with predetermined penalty coefficients for their violations. The key idea is the “surrogate optimization” concept that ensures multiplier convergence within “surrogate” Lagrangian relaxation as long as the “surrogate optimality condition” is satisfied without the need to optimally solve the “relaxed problem.” Consequently, subproblems can still be formed and optimized when soft constraints are not relaxed, leading to a drastically reduced number of multipliers and improved performance. To further enhance the method, a parallel version is developed. Testing results on the Polish system demonstrate the effectiveness and robustness of both the sequential and parallel versions at finding high-quality solutions within the time limit.

Download Full-text

Empirical Investigation of Aids for Non-Programming Users in Developing Cost Effective Requirements Specifications

Proceedings of the Human Factors Society Annual Meeting ◽

10.1177/154193128402800120 ◽

1984 ◽

Vol 28 (1) ◽

pp. 67-71

Author(s):

Edward M. Connelly

Keyword(s):

Error Control ◽

Cost Effective ◽

Complex Problem ◽

Total System ◽

Problem Complexity ◽

System Cost ◽

Requirements Specifications ◽

Computational Support ◽

Software Product ◽

Improved Performance

The difficulties of the non-programming user in developing quality software-requirements specifications are well known and described in the literature. Typically, the user will work with a software expert to develop the specifications. During this process the user must learn new terms and concepts, and must attempt to identify the required functions of the resulting software product. The goal of this investigation was to evaluate the capability of non-programming users (in this case experienced inventory managers) to develop specifications for an inventory error-control system. Participants specified tests from a set of available tests to detect possible errors in inventory change-records, i.e., in inventory updates. Costing-aids were provided that were analogs of aids that are expected to be presently available. The costing-aids provided an increasing data on system cost: the total system cost, the total system cost plus the costs of each part of the system, and an automatic sort of previous designs according to cost. Results shewed that problem-complexity had a strong effect on performance; greater problem-complexity resulted in more costly designs. Further, the more complete costing-aids tended to degrade performance on the simple problems, yet they improved performance on the more complex problem. It was concluded that the ability of non-programming users to develop least-cost requirements specifications was poor when using any of the aids that were made available. The experimental results, however, suggested new approaches for procedural and computational support for the non-programming user, that could lead to more suitable costing-aids.

Download Full-text

PARALLEL NUMERICAL MODELLING OF SHORT LASER PULSE COMPRESSION

Mathematical Modelling and Analysis ◽

10.3846/13926292.2004.9637246 ◽

2005 ◽

Vol 9 (2) ◽

pp. 115-126 ◽

Cited By ~ 1

Author(s):

R. Čiegis ◽

A. Dement'ev ◽

G. Šilko

Keyword(s):

Initial Phase ◽

Pulse Compression ◽

Numerical Algorithms ◽

Parallel Computers ◽

Problem Complexity ◽

Splitting Scheme ◽

Stimulated Scattering ◽

Computational Region ◽

Parallel Version ◽

Parallel Numerical Algorithms

In this paper we investigate parallel numerical algorithms for solution of the transient stimulated scattering processes. A new symmetrical splitting scheme is proposed and a parallel version is given. The efficiency of the parallel algorithm is investigated for two cases. The first one describes a case when the computation region is constant during the whole time of computations. The second one describes the initial phase of the process, when the computational region increases linearly in time. In order to distribute more evenly jobs between processors a dynamical the grid redistribution algorithm is is used. We also give a proof of one result about optimal static grid distribution in the case of linearly increased problem complexity. The results of computations are presented. They were obtained on different parallel computers and clusters of workstations. Nagrinejamas priverstines Brijueno sklaidos fokusuotuose pluoštuose uždavinio lygiagretusis skaitinis sprendimo algoritmas. Sukonstruota simetrinio skaidymo baigtiniu skirtumu schema, kurios tikslumas yra antrosios eiles. Lygiagretusis algoritmas gautas naudojant duomenu lygiagretumo paradigma. Detaliai nagrinejamas dinamiškai didejančio sudetingumo uždavinys, modeliuojantis Brijueno sklaidos procesa, kai neužduodama kraštine salyga Stokso bangai. Irodyta hipoteze apie vieno stacionaraus blokinio duomenu paskirstymo algoritmo op‐timaluma. Eksperimentiškai ištirtas dinaminis duomenu perskirstymo algoritmas, patvirtintas jo efektyvumas net ir fiksuoto dydžio uždaviniams. Darbe pateikti skaitinio eksperimento, atlikto naudojant VGTU 20 procesoriu klasteri, rezultatai. Jie patvirtino gautuosius teorinius rezultatus, išsam us fizikiniai rezultatai bus išspausdinti kituose darbuose.

Download Full-text

The freckle plot (daily turnaround time chart): a technique for timely and effective quality improvement of test turnaround times

Clinical Chemistry ◽

10.1093/clinchem/39.6.1054 ◽

1993 ◽

Vol 39 (6) ◽

pp. 1054-1059 ◽

Cited By ~ 4

Author(s):

T G Pellar ◽

P J Ward ◽

J F Tuckerman ◽

A R Henderson

Keyword(s):

Quality Assurance ◽

Quality Improvement ◽

Confidence Interval ◽

Turnaround Time ◽

Daily Basis ◽

Time Limit ◽

Remedial Action ◽

Monthly Basis ◽

Conventional Tests ◽

Test Delay

Abstract Test turnaround times are often monitored on a monthly basis. However, such an interval usually means that not all causes for delay in test reporting can be unequivocally identified for institution of remedial action. We have devised a daily chart--the freckle plot--that graphically displays the test turnaround times by laboratory receipt time. Different symbols are used to designate specimens reported within the test's turnaround time limit, those within 10 min beyond that limit, and those well outside the limit. These categories are adjustable to suit different limits of stringency. Freckle plots are produced on a daily basis and can be used to track down causes for test delays. Using the 1-h turnaround time "stat" potassium test as a model, we found 16 causes for test delay, of which 9 were potentially remediable. By applying these remedies, we were able to increase test compliance, in the day shift, from 91.5% (95% confidence interval 88.8%-93.7%) to 97.6% (95% confidence interval 96.4-98.55%), which is significant at P < 10(-7). This daily plot is a useful quality assurance tool, supplementing the more conventional tests used to ensure laboratory quality improvement.

Download Full-text

Toward The Simultaneous Correction of Spherical and Chromatic Aberration in Electron Optics by Means of an Electrostatic Electron Mirror

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100179786 ◽

1990 ◽

Vol 48 (1) ◽

pp. 206-207

Author(s):

Gertrude. F. Rempfer

Keyword(s):

Chromatic Aberration ◽

Transverse Magnetic ◽

Objective Lens ◽

Ion Imaging ◽

Corrected Image ◽

Electric And Magnetic Fields ◽

Chromatic Aberrations ◽

Improved Performance ◽

Electron Microscopes ◽

Image Planes

Optimum performance in electron and ion imaging instruments, such as electron microscopes and probe-forming instruments, in most cases depends on a compromise either between imaging errors due to spherical and chromatic aberrations and the diffraction error or between the imaging errors and the current in the image. These compromises result in the use of very small angular apertures. Reducing the spherical and chromatic aberration coefficients would permit the use of larger apertures with resulting improved performance, granted that other problems such as incorrect operation of the instrument or spurious disturbances do not interfere. One approach to correcting aberrations which has been investigated extensively is through the use of multipole electric and magnetic fields. Another approach involves the use of foil windows. However, a practical system for correcting spherical and chromatic aberration is not yet available.Our approach to correction of spherical and chromatic aberration makes use of an electrostatic electron mirror. Early studies of the properties of electron mirrors were done by Recknagel. More recently my colleagues and I have studied the properties of the hyperbolic electron mirror as a function of the ratio of accelerating voltage to mirror voltage. The spherical and chromatic aberration coefficients of the mirror are of opposite sign (overcorrected) from those of electron lenses (undercorrected). This important property invites one to find a way to incorporate a correcting mirror in an electron microscope. Unfortunately, the parts of the beam heading toward and away from the mirror must be separated. A transverse magnetic field can separate the beams, but in general the deflection aberrations degrade the image. The key to avoiding the detrimental effects of deflection aberrations is to have deflections take place at image planes. Our separating system is shown in Fig. 1. Deflections take place at the separating magnet and also at two additional magnetic deflectors. The uncorrected magnified image formed by the objective lens is focused in the first deflector, and relay lenses transfer the image to the separating magnet. The interface lens and the hyperbolic mirror acting in zoom fashion return the corrected image to the separating magnet, and the second set of relay lenses transfers the image to the final deflector, where the beam is deflected onto the projection axis.

Download Full-text

Personal Audio System: Hearing Symptoms, Habits, and Sound Pressure Levels Measured in Real Ear and a Manikin

Journal of Speech Language and Hearing Research ◽

10.1044/2020_jslhr-19-00053 ◽

2020 ◽

Vol 63 (6) ◽

pp. 2016-2026

Author(s):

Tamara R. Almeida ◽

Clayton H. Rocha ◽

Camila M. Rabelo ◽

Raquel F. Gomes ◽

Ivone F. Neves-Lobo ◽

...

Keyword(s):

Sound Pressure ◽

Daily Basis ◽

Cross Sectional Study ◽

Normal Hearing ◽

Chi Square ◽

Cross Sectional ◽

The Real ◽

Significant Difference ◽

Sound Pressure Levels ◽

Audio System

Purpose The aims of this study were to characterize hearing symptoms, habits, and sound pressure levels (SPLs) of personal audio system (PAS) used by young adults; estimate the risk of developing hearing loss and assess whether instructions given to users led to behavioral changes; and propose recommendations for PAS users. Method A cross-sectional study was performed in 50 subjects with normal hearing. Procedures included questionnaire and measurement of PAS SPLs (real ear and manikin) through the users' own headphones and devices while they listened to four songs. After 1 year, 30 subjects answered questions about their usage habits. For the statistical analysis, one-way analysis of variance, Tukey's post hoc test, Lin and Spearman coefficients, the chi-square test, and logistic regression were used. Results Most subjects listened to music every day, usually in noisy environments. Sixty percent of the subjects reported hearing symptoms after using a PAS. Substantial variability in the equivalent music listening level (Leq) was noted ( M = 84.7 dBA; min = 65.1 dBA, max = 97.5 dBA). A significant difference was found only in the 4-kHz band when comparing the real-ear and manikin techniques. Based on the Leq, 38% of the individuals exceeded the maximum daily time allowance. Comparison of the subjects according to the maximum allowed daily exposure time revealed a higher number of hearing complaints from people with greater exposure. After 1 year, 43% of the subjects reduced their usage time, and 70% reduced the volume. A volume not exceeding 80% was recommended, and at this volume, the maximum usage time should be 160 min. Conclusions The habit of listening to music at high intensities on a daily basis seems to cause hearing symptoms, even in individuals with normal hearing. The real-ear and manikin techniques produced similar results. Providing instructions on this topic combined with measuring PAS SPLs may be an appropriate strategy for raising the awareness of people who are at risk. Supplemental Material https://doi.org/10.23641/asha.12431435

Download Full-text