A Biased Random Key Genetic Algorithm Approach for Unit Commitment Problem

A Biased Random Key Genetic Algorithm (BRKGA) is proposed to find solutions for the unit commitment problem. In this problem, one wishes to schedule energy production on a given set of thermal generation units in order to meet energy demands at minimum cost, while satisfying a set of technological and spinning reserve constraints. In the BRKGA, solutions are encoded by using random keys, which are represented as vectors of real numbers in the interval [0, 1]. The GA proposed is a variant of the random key genetic algorithm, since bias is introduced in the parent selection procedure, as well as in the crossover strategy. Tests have been performed on benchmark large-scale power systems of up to 100 units for a 24 hours period. The results obtained have shown the proposed methodology to be an effective and efficient tool for finding solutions to large-scale unit commitment problems. Furthermore, from the comparisons made it can be concluded that the results produced improve upon some of the best known solutions

Low-cost inorganic cation exchange membrane for electrodialysis: optimum processing temperature for the cation exchanger

The optimum temperature for fixing zirconium phosphate, obtained by precipitation, on a low-cost ceramic support was determined in order to obtain an inorganic cation exchange membrane for electrodialysis. Zirconium phosphate ion exchange capacity maximised between 450 and 550°C, thus it was considered the optimum processing temperature. The origin of this maximum was investigated by means of X-ray diffraction and termogravimetry and evolved gas analysis. Zirconium phosphate formation by precipitation in the porous network of the support was verified by scanning electron microscopy and energy dispersive X-ray analysis and mercury intrusion porosimetry. The membrane obtained after thermal treatment at 450°C displayed selectivity to the cations present in the spent rinse water of the chromium plating process. This property allows the recovery of chromium by removing the cations through the cation exchange ceramic membrane.The authors wish to express their gratitude to the Spanish Ministry of Science and Innovation for the support given to the research study (National Basic Research Programme, Ref. CTQ2008-06750-C02-02), as well as for the FPU student grant awarded to one of the authors (Ref.: AP2009-4409).Mestre, S.; Sales, S.; Palacios, M.; Lorente, M.; Mallol, G.; Pérez-Herranz, V. (2013). Low-cost inorganic cation exchange membrane for electrodialysis: optimum processing temperature for the cation exchanger. Desalination and Water Treatment. 51(16-18):3317-3324. https://doi.org/10.1080/19443994.2012.749177S331733245116-18Strathmann, H. (2010). Electromembrane Processes: Basic Aspects and Applications. Comprehensive Membrane Science and Engineering, 391-429. doi:10.1016/b978-0-08-093250-7.00048-7Drioli, E., & Fontananova, E. (s. f.). Integrated Membrane Processes. Membrane Operations, 265-283. doi:10.1002/9783527626779.ch12Strathmann, H. (s. f.). Fundamentals in Electromembrane Separation Processes. Membrane Operations, 83-119. doi:10.1002/9783527626779.ch5Alberti, G., Casciola, M., Costantino, U., & Levi, G. (1978). Inorganic ion exchange membranes consisting of microcrystals of zirconium phosphate supported by Kynar®. Journal of Membrane Science, 3(2), 179-190. doi:10.1016/s0376-7388(00)83021-5Semiat, R., & Hasson, D. (s. f.). Seawater and Brackish-Water Desalination with Membrane Operations. Membrane Operations, 221-243. doi:10.1002/9783527626779.ch10Bregman, J. ., & Braman, R. . (1965). Inorganic ion exchange membranes. Journal of Colloid Science, 20(9), 913-922. doi:10.1016/0095-8522(65)90064-4Bishop, H. K., Bittles, J. A., & Guter, G. A. (1969). Investigation of inorganic ion exchange membranes for electrodialysis. Desalination, 6(3), 369-380. doi:10.1016/s0011-9164(00)80226-xRajan, K. S., Boies, D. B., Casolo, A. J., & Bregman, J. . (1966). Inorganic ion-exchange membranes and their application to electrodialysis. Desalination, 1(3), 231-246. doi:10.1016/s0011-9164(00)80255-6INAMUDDIN, KHAN, S., SIDDIQUI, W., & KHAN, A. (2007). Synthesis, characterization and ion-exchange properties of a new and novel ‘organic–inorganic’ hybrid cation-exchanger: Nylon-6,6, Zr(IV) phosphate. Talanta, 71(2), 841-847. doi:10.1016/j.talanta.2006.05.042HELEN, M., VISWANATHAN, B., & MURTHY, S. (2007). Synthesis and characterization of composite membranes based on α-zirconium phosphate and silicotungstic acid. Journal of Membrane Science, 292(1-2), 98-105. doi:10.1016/j.memsci.2007.01.018Yu.S. Dzyaz’ko, V.N. Belyakov, N.V. Stefanyak, S.L. Vasilyuk, Anion-exchange properties of composite ceramic membranes containing hydrated zirconium dioxide, Russ. J. Appl. Chem. 79 (2006) 769–773.Linkov, V. ., & Belyakov, V. . (2001). Novel ceramic membranes for electrodialysis. Separation and Purification Technology, 25(1-3), 57-63. doi:10.1016/s1383-5866(01)00090-9Linkov, V. M., Dzyaz’ko, Y. S., Belyakov, V. N., & Atamanyuk, V. Y. (2007). Inorganic composite membranes for electrodialytic desaltination. Russian Journal of Applied Chemistry, 80(4), 576-581. doi:10.1134/s1070427207040118El-Sourougy, M. R., Zaki, E. E., & Aly, H. F. (1997). Transport characteristics of ceramic supported zirconium phosphate membrane. Journal of Membrane Science, 126(1), 107-113. doi:10.1016/s0376-7388(96)00273-6Sánchez, E., Mestre, S., Pérez-Herranz, V., & García-Gabaldón, M. (2005). Síntesis de membranas cerámicas para la regeneración de baños de cromado agotados. Boletín de la Sociedad Española de Cerámica y Vidrio, 44(6), 409-414. doi:10.3989/cyv.2005.v44.i6.340Sánchez, E., Mestre, S., Pérez-Herranz, V., Reyes, H., & Añó, E. (2006). Membrane electrochemical reactor for continuous regeneration of spent chromium plating baths. Desalination, 200(1-3), 668-670. doi:10.1016/j.desal.2006.03.475Alberti, G., Casciola, M., Costantino, U., & Vivani, R. (1996). Layered and pillared metal(IV) phosphates and phosphonates. Advanced Materials, 8(4), 291-303. doi:10.1002/adma.19960080405Alberti, G., & Torracca, E. (1968). Crystalline insoluble salts of polybasic metals - II. Synthesis of crystalline zirconium or titanium phosphate by direct precipitation. Journal of Inorganic and Nuclear Chemistry, 30(1), 317-318. doi:10.1016/0022-1902(68)80096-xTrobajo, C., Khainakov, S. A., Espina, A., & García, J. R. (2000). On the Synthesis of α-Zirconium Phosphate. Chemistry of Materials, 12(6), 1787-1790. doi:10.1021/cm0010093Alberti, G. (1978). Syntheses, crystalline structure, and ion-exchange properties of insoluble acid salts of tetravalent metals and their salt forms. Accounts of Chemical Research, 11(4), 163-170. doi:10.1021/ar50124a007Rajeh, A. O., & szirtes, L. (1995). Investigations of crystalline structure of gamma-zirconium phosphate. Journal of Radioanalytical and Nuclear Chemistry Articles, 196(2), 319-322. doi:10.1007/bf02038050Krogh Andersen, A. M., Norby, P., Hanson, J. C., & Vogt, T. (1998). Preparation and Characterization of a New 3-Dimensional Zirconium Hydrogen Phosphate, τ-Zr(HPO4)2. Determination of the Complete Crystal Structure Combining Synchrotron X-ray Single-Crystal Diffraction and Neutron Powder Diffraction. Inorganic Chemistry, 37(5), 876-881. doi:10.1021/ic971060hFeng, Y., He, W., Zhang, X., Jia, X., & Zhao, H. (2007). The preparation of nanoparticle zirconium phosphate. Materials Letters, 61(14-15), 3258-3261. doi:10.1016/j.matlet.2006.11.132Clearfield, A. (2000). INORGANIC ION EXCHANGERS, PAST, PRESENT, AND FUTURE. Solvent Extraction and Ion Exchange, 18(4), 655-678. doi:10.1080/07366290008934702Szirtes, L., Shakshooki, S. K., Szeleczky, A. M., & Rajeh, A. O. (1998). Thermoanalyncal Investigation of Some Layered Zirconium Salts and Their Various Derivatives I. Journal of Thermal Analysis and Calorimetry, 51(2), 503-515. doi:10.1007/bf03340188Al-Othman, A., Tremblay, A. Y., Pell, W., Letaief, S., Burchell, T. J., Peppley, B. A., & Ternan, M. (2010). Zirconium phosphate as the proton conducting material in direct hydrocarbon polymer electrolyte membrane fuel cells operating above the boiling point of water. Journal of Power Sources, 195(9), 2520-2525. doi:10.1016/j.jpowsour.2009.11.052Thakkar, R., Patel, H., & Chudasama, U. (2007). A comparative study of proton transport properties of zirconium phosphate and its metal exchanged phases. Bulletin of Materials Science, 30(3), 205-209. doi:10.1007/s12034-007-0036-3Jiang, P., Pan, B., Pan, B., Zhang, W., & Zhang, Q. (2008). A comparative study on lead sorption by amorphous and crystalline zirconium phosphates. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 322(1-3), 108-112. doi:10.1016/j.colsurfa.2008.02.035García-Gabaldón, M., Pérez-Herranz, V., García-Antón, J., & Guiñón, J. L. (2009). Use of ion-exchange membranes for the removal of tin from spent activating solutions. Desalination and Water Treatment, 3(1-3), 150-156. doi:10.5004/dwt.2009.453García-Gabaldón, M., Pérez-Herranz, V., García-Antón, J., & Guiñón, J. L. (2009). Effect of hydrochloric acid on the transport properties of tin through ion-exchange membranes. Desalination and Water Treatment, 10(1-3), 73-79. doi:10.5004/dwt.2009.69

Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47×10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society

Search for Tensor, Vector, and Scalar Polarizations in the Stochastic Gravitational-Wave Background

The detection of gravitational waves with Advanced LIGO and Advanced Virgo has enabled novel tests of general relativity, including direct study of the polarization of gravitational waves. While general relativity allows for only two tensor gravitational-wave polarizations, general metric theories can additionally predict two vector and two scalar polarizations. The polarization of gravitational waves is encoded in the spectral shape of the stochastic gravitational-wave background, formed by the superposition of cosmological and individually unresolved astrophysical sources. Using data recorded by Advanced LIGO during its first observing run, we search for a stochastic background of generically polarized gravitational waves. We find no evidence for a background of any polarization, and place the first direct bounds on the contributions of vector and scalar polarizations to the stochastic background. Under log-uniform priors for the energy in each polarization, we limit the energy densities of tensor, vector, and scalar modes at 95% credibility to Ω0T<5.58×10-8, Ω0V<6.35×10-8, and Ω0S<1.08×10-7 at a reference frequency f0=25 Hz. © 2018 American Physical Society

Alignment of the CMS silicon tracker during commissioning with cosmic rays

This is the Pre-print version of the Article. The official published version of the Paper can be accessed from the link below - Copyright @ 2010 IOPThe CMS silicon tracker, consisting of 1440 silicon pixel and 15 148 silicon strip detector modules, has been aligned using more than three million cosmic ray charged particles, with additional information from optical surveys. The positions of the modules were determined with respect to cosmic ray trajectories to an average precision of 3–4 microns RMS in the barrel and 3–14 microns RMS in the endcap in the most sensitive coordinate. The results have been validated by several studies, including laser beam cross-checks, track fit self-consistency, track residuals in overlapping module regions, and track parameter resolution, and are compared with predictions obtained from simulation. Correlated systematic effects have been investigated. The track parameter resolutions obtained with this alignment are close to the design performance.This work is supported by FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)

Commissioning and performance of the CMS pixel tracker with cosmic ray muons

This is the Pre-print version of the Article. The official published verion of the Paper can be accessed from the link below - Copyright @ 2010 IOPThe pixel detector of the Compact Muon Solenoid experiment consists of three barrel layers and two disks for each endcap. The detector was installed in summer 2008, commissioned with charge injections, and operated in the 3.8 T magnetic field during cosmic ray data taking. This paper reports on the first running experience and presents results on the pixel tracker performance, which are found to be in line with the design specifications of this detector. The transverse impact parameter resolution measured in a sample of high momentum muons is 18 microns.This work is supported by FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)

Erratum: "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo" (2021, ApJ, 909, 218)

[no abstract available

Performance of the CMS drift-tube chamber local trigger with cosmic rays

The performance of the Local Trigger based on the drift-tube system of the CMS experiment has been studied using muons from cosmic ray events collected during the commissioning of the detector in 2008. The properties of the system are extensively tested and compared with the simulation. The effect of the random arrival time of the cosmic rays on the trigger performance is reported, and the results are compared with the design expectations for proton-proton collisions and with previous measurements obtained with muon beams

Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3b

We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC-2020 March 27 17:00 UTC). We conduct two independent searches: A generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence for subthreshold gravitational-wave signals associated with this GRB ensemble either. We use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each GRB. Finally, we constrain the population of low-luminosity short GRBs using results from the first to the third observing runs of Advanced LIGO and Advanced Virgo. The resulting population is in accordance with the local binary neutron star merger rate. © 2022. The Author(s). Published by the American Astronomical Society