313 research outputs found
Where Does the Density Localize? Convergent Behavior for Global Hybrids, Range Separation, and DFT+U
Approximate density functional theory (DFT) suffers from many-electron self-
interaction error, otherwise known as delocalization error, that may be
diagnosed and then corrected through elimination of the deviation from exact
piecewise linear behavior between integer electron numbers. Although paths to
correction of energetic delocalization error are well- established, the impact
of these corrections on the electron density is less well-studied. Here, we
compare the effect on density delocalization of DFT+U, global hybrid tuning,
and range- separated hybrid tuning on a diverse test set of 32 transition metal
complexes and observe the three methods to have qualitatively equivalent
effects on the ground state density. Regardless of valence orbital diffuseness
(i.e., from 2p to 5p), ligand electronegativity (i.e., from Al to O), basis set
(i.e., plane wave versus localized basis set), metal (i.e., Ti, Fe, Ni) and
spin state, or tuning method, we consistently observe substantial charge loss
at the metal and gain at ligand atoms (ca. 0.3-0.5 e or more). This charge loss
at the metal is preferentially from the minority spin, leading to increasing
magnetic moment as well. Using accurate wavefunction theory references, we
observe that a minimum error in partial charges and magnetic moments occur at
higher tuning parameters than typically employed to eliminate energetic
delocalization error. These observations motivate the need to develop
multi-faceted approximate-DFT error correction approaches that separately treat
density delocalization and energetic errors in order to recover both correct
density and magnetization properties.Comment: 34 pages, 11 figure
H∞ control for networked systems with random communication delays
Copyright [2006] IEEE. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.This note is concerned with a new controller design problem for networked systems with random communication delays. Two kinds of random delays are simultaneously considered: i) from the controller to the plant, and ii) from the sensor to the controller, via a limited bandwidth communication channel. The random delays are modeled as a linear function of the stochastic variable satisfying Bernoulli random binary distribution. The observer-based controller is designed to exponentially stabilize the networked system in the sense of mean square, and also achieve the prescribed H∞ disturbance attenuation level. The addressed controller design problem is transformed to an auxiliary convex optimization problem, which can be solved by a linear matrix inequality (LMI) approach. An illustrative example is provided to show the applicability of the proposed method
Robust H∞ control with missing measurements and time delays
Copyright [2007] IEEE. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.In this technical note, the robust control problem is investigated for a class of stochastic uncertain discrete time-delay systems with missing measurements. The parameter uncertainties enter into the state matrices, and the missing measurements are described by a binary switching sequence satisfying a conditional probability distribution. The purpose of the problem is to design a full-order dynamic feedback controller such that, for all possible missing observations and admissible parameter uncertainties, the closed-loop system is asymptotically mean-square stable and satisfies the prescribed performance constraint. Delay-dependent conditions are derived under which the desired solution exists, and the controller parameters are designed by solving a linear matrix inequality (LMI). A numerical example is provided to illustrate the usefulness of the proposed design method
The Strategic Adaptation of Chinese-Manadonese in the Reform Era
This article is a further discussion of previous research which is a pilot project to observe patterns of cultural interaction within the Chinese community in Indonesia as a part of a project to understand the phenomenon of the multicultural society during the New Order Era. The specific target of this research is to study the socio-cultural interactions within the Chinese community in Manado during the Reform Era (2000-2014). This research aims to study the strategic adaptation of the Chinese in Manado, by analysing the obstacles and opportunities in their socio-cultural interaction with the locals. Using data from field research and literature studies, this qualitative research applies an ethnographic approach by observing various actions in their socio-cultural interactions
Penerapan Pembelajaran Kontekstual Untuk Meningkatkan Kemampuan Berpikir Logis Dan Pemahaman Peserta Didik SMP Pada Materi Sifat-sifat Cahaya
Penelitian penerapan pembelajaran kontekstual pada materi sifat-sifat cahaya telah dilakukan di SMP Negeri I Meulaboh, Aceh Barat menggunakan metode eksperimen semu dengan desain pretest dan posttest group. Teknik pengambilan sampel secara purposif dengan membandingkan nilai rata-rata tiap kelas pada mata pelajaran sains. Dua kelas yang memiliki nilai yang sama dipilih sebagai kelas eksperimen dan kontrol. Pengumpulan data kemampuan berpikir logis (KBL) dan pemahaman peserta didik dilakukan melalui pretest dan posttest. Data KBL juga diperoleh dari lembar observasi dalam PBM sains. Uji data pretest KBL dan pemahaman kedua kelas menunjukkan bahwa salah satu data tidak berdistribusi normal, sehingga dipergunakan uji Mann-Whitney untuk menguji hipotesis penelitian. N-gain rata-rata KBL untuk kedua kelas berkategori tinggi dan uji hipotesis diperoleh z-hitung>z-tabel (2,87 > 2,58) yang artinya pembelajaran kontekstual dapat meningkatkan KBL secara lebih baik. Hasil observasi juga menunjukkan bahwa nilai rata-rata KBL pada kelas eksperimen lebih tinggi dari pada kelas kontrol. N-gain rata-rata pemahaman untuk kedua kelas berkategori sedang dan uji hipotesis menunjukkan z-hitung>z-tabel (2,92>2,33) yang artinya pembelajaran konstekstual meningkatkan kemampuan pemahaman peserta didik secara lebih baik. Dari hasil penelitian dapat disimpulkan bahwa pembelajaran kontekstual secara signifikan dapat meningkatkan KBL dan pemahaman peserta didik secara lebih baik pada materi sifat-sifat cahay
Optimal Solvent Design for Extractive Distillation Processes: A Multiobjective Optimization-Based Hierarchical Framework
Extractive distillation
is a widely accepted and commercialized
process for separating azeotropic mixtures compared to conventional
distillation. The search for high-performing solvents, or entrainers,
needed in extractive distillation is a challenging task. The heuristic
guideline or experiment-based method for the screening of entrainers
is usually not very efficient and limited to the existing, well-known
solvents. In this contribution, we propose a multistage theoretical
framework to design solvents for extractive distillation. A multiobjective
optimization-based computer-aided molecular design (MOO-CAMD) method
is developed and used to find a list of Pareto-optimal solvents. In
the MOO-CAMD method, two important solvent properties (i.e., selectivity
and capacity) that determine the extractive distillation efficiency
are simultaneously optimized. The next step involves a further screening
of the Pareto-optimal solvents by performing rigorous thermodynamic
calculation and analysis. Finally, for each of the remaining solvents,
the extractive distillation process is optimally designed, and the
best candidate showing the highest process performance is ultimately
identified. The overall design framework is illustrated through an
example of the n-hexane and methanol separation
Analisis Tingkat Kontaminasi Permukaan Daerah Kerja dan Laju Paparan Radiasi pada Instalasi Kedokteran Nuklir
The surface contamination of the work area and the rate of radiation exposure at nuclear medicine installation have an effect to the safety workers and the society directly or indirectly. This study aims to analyze the level of surface contamination and the rate of radiation exposure on the nuclear medicine installation and to identify the activity of half time 99mTc and 131I. The used method is measuring the surface contamination of the work area caused by the use of radiopharmaceutical through the distance between the detector window and the 3 cm measured region. Meanwhile, the rate of radiation exposures is used to measure the sides of each room with a distance 1 meter in the area control and to measure the activity of radioisotope that is monitored once every an hour for 6.03 hours to 99mTc and every day for 8 days to 131I of the initial measurement and compares with the result calculation. The measurement result of the level of the surface contamination in various areas of all rooms is 0.000-5.272 Bq/cm2 and it is classified into low to medium level of contamination. The measurement result of the rate of radiation exposure in the control area is 0.022-1.404 µSv/h which is still classified under 10 µSv/h. So, it can be concluded that it is safe for workers and other patients. The use of radioisotope on the nuclear medicine installation in accordance with their needs and always consider to the principles of the radiation protection, therefore the level of contamination and the rate of radiation exposure is low. The result of the measurement and the calculation of the activity of 99mTc are decays into a half after 6.03 hours and the activity of 131I is decays a half after 8 days
Stable branches of a solution for a fermion on domain wall
We discuss the case when a fermion occupies an excited non-zero frequency
level in the field of domain wall. We demonstrate that a solution exists for
the coupling constant in the limited interval . We
show that indeed there are different branches of stable solution for in
this interval. The first one corresponds to a fermion located on the domain
wall (). The second branch, which belongs to the interval
, describes a polarized fermion off the domain
wall. The third branch with describes an excited antifermion in
the field of the domain wall.Comment: 15 pages, 7 figures, references adde
Improving Soil Chemical Properties by NPK Fertilizer Application and Residual Rice Husk Biochar Effect on Irrigation Paddy Field
The research objective was to study effects of NPK fertilizer and biochar residue on soil chemical properties of paddy on second planting. Experiment was arranged in a randomized complete block design in a factorial design with four replications. Biochar consisted of two levels, i.e. without biochar residue and with biochar residue 10 ton ha-1. NPK fertilizer consisted of three levels, i.e. without NPK, NPK 60 kg ha-1, and NPK 120 kg ha-1. The result showed that application NPK fertilizer and biochar residue on second planting increase total N 22.22%, available P 12.18%, available K 17.50%, and organic C 56.69% compare than first plantin
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