Предсказательное моделирование массообменного технологического объекта с использованием алгоритма чередующихся условных математических ожиданий

Рассматривается задача построения модели для оценки показателя качества выходного продукта нелинейного массообменного технологического объекта (МТО) на основе экспериментальных данных. Для анализа структурной идентифицируемости исследуемого процесса и выявления факторов, влияющих на точность индекса структурной идентифицируемости модели, предлагается методика на основе алгоритма чередующихся условных математических ожиданий (alternating conditional expectation -- АСЕ). Определяется пороговое значение индекса структурной идентифицируемости на основе аналитической модели объекта, т.е. с учетом физикохимических особенностей рассматриваемого МТО. Применение предлагаемого подхода проиллюстрировано на синтетических и экспериментальных данных.

Understanding the operating landscape of the global airline industry: A DEA integrated alternating conditional expectation approach

Purpose: This study investigates the relationships between service efficiency in 5 major cost centres (namely, business orientation, network coverage, physical resources, maintenance, repair and overhaul (MRO), and human resources) and profitability in the global airline industry.Design/methodology/approach: The study integrates the Slack-based Model (SBM) of Data Envelopment Analysis (DEA) with the Alternating Conditional Expectation (ACE) regression to understand the relationships between an airline’s profitability and its efficiencies in 5 identified operations areas.Findings: Based on the observational data obtained from 75 international airlines, the relationships between operational performances and profitability are found to be curvilinear and contingent on an airline’s operating model.Research limitations/implications: The omission of non-IATA airlines and many low cost carriers may hinder a holistic view of the airline industry.Practical implications: Management can influence the profitability of an airline through its strategic operations decisions that affect an airline’s cost, service quality, and financial structure after the influences of location and size have set the stage. Airlines pursuing cost leadership should seek to increase productivity especially in MRO, human resources and physical resources; whereas airlines pursuing service differentiation may choose to provide quality service at lower efficiencies or pursue an approach to improve quality and efficiencies simultaneously.Originality/value: Identifying operations practices that are consistent with a firm’s competitive priorities is important in the multifaceted service environment today. An integrated SBM-ACE regression model, which permits different input-output mix, variable return to scale and non-linear relationship, is proposed and applied to analyze the profit impact of service efficiencies in the five key operations areas.

ECC Design Based on Uniform Design Test Method and Alternating Conditional Expectation

Engineered cementitious composites (ECC) have higher ultimate tensile strains than normal concrete. The mechanical properties of ECC strongly depend on raw materials and the mix proportions. The uniform design test method and alternating conditional expectation, which is a nonparametric regression analysis method, were used to design the ECC mix proportion. According to the regression analysis, the optimized W/B, S/B, and F/B ranges could be obtained as 0.35–0.42, 0.25–0.3, and 0.02, respectively. The tested proportions for validation were randomly adopted within the range of W/B, S/B, and F/B. The uniaxial compression, tension, and four-point bending tests were conducted to verify the material behaviour of the designed ECC. Results showed that all the specimens had large ultimate tensile strains and high fracture energy capacities, and strain hardening was also observed. The fibers were found to be uniformly distributed in the specimens by using a scanning electron microscope. This paper may provide theoretical and practical guidance for the ECC and other cement-based material mix proportion design.

A Graphical Alternating Conditional Expectation to Predict Hydrate Phase Equilibrium Conditions for Sweet and Sour Natural Gases

Natural gas hydrate has been widely of concern due to its great potential in application to address problems including gas storage, transmission, separation techniques, and also as energy resource. Accurate prediction of hydrate formation phase equilibrium conditions is essential for the optimized design during natural gas production, processing, and transportation. In this study, a novel graphical alternating conditional expectation (ACE) algorithm was proposed to predict hydrate formation phase equilibrium conditions for sweet and sour natural gases. The accuracy and performance of the presented ACE model were evaluated using 1055 data points (688, 249, and 118 data points for sweet natural gas, CO2-CH4, and H2S-CO2-CH4 systems, respectively) collected from literature. Meanwhile, a comparative study was conducted between the ACE model and commonly used correlations, including thirteen models for sweet natural gases, three models for CO2-CH4 binary system, and seven thermodynamic models for H2S-CO2-CH4 ternary system. The obtained results indicated that the proposed ACE model produces the best results in prediction of hydrate phase equilibrium temperature for sweet natural gases and pressure for CO2-CH4 system with average absolute relative deviation (AARD) of 0.134% and 2.75%, respectively. The proposed quick and explicit ACE model also provides a better performance in prediction of hydrate phase equilibrium pressure for H2S-CO2-CH4 ternary systems with AARD=5.20% compared with seven thermodynamic methods considered in this work, except for CPA/Electrolyte/Chen–Guo combined model (AARD=4.45%).

PENENTUAN FLOW UNIT BATUAN RESERVOIR PADA LAPANGAN RN

<p>Batuan karbonat merupakan salah satu batuan yang sangat bagus sebagai batuan reservoar, namun batuan ini memiliki tingkat heterogenitas yang sangat tinggi dibandingkan dengan batupasir sehingga memerlukan pendekatan dengan melakukan <em>rock typing. </em>Pada umumnya, indentifikasi <em>rock type </em>membutuhkan hasil pengukuran dari <em>core </em>dengan menggunakan beberapa metode yang telah ada. Namun, pada sumur-sumur yang tidak memiliki data <em>core </em>sangat sulit untuk menerapkan metode tersebut. Penelitian ini dilakukan dalam upaya untuk menentukan <em>Hydraulic Flow Unit </em>(HFU) reservoar pada sumur yang memiliki data <em>core </em>dengan menggunakan parameter <em>Flow Zone Indicator </em>(FZI) dan metode regresi non-parametrik yang disebut <em>Alternating Conditional Expectation </em>(ACE) pada sumur yang tidak memiliki data <em>core</em>. Dari hasil penelitian, reservoar pada lapangan RN dapat dikelompokkan menjadi delapan flow unit. Delapan flow unit tersebut masing-masing memiliki permeabilitas sebagai fungsi dari porositas yang telah divalidasi dengan mengaplikasikannya pada sumur. Dengan menggunakan metode ACE, kita dapat menentukan <em>Hydraulic Flow Unit </em>pada sumur yang tidak memiliki data <em>core </em>dengan menggunakan data log. Setelah FZI dihitung dari data <em>log </em>dan divalidasi dengan data <em>core </em>terlihat bahwa hasil dari metode tersebut menghasilkan korelasi yang cukup baik (R² = 0.84), sehingga metode tersebut cukup dapat diaplikasikan pada sumur-sumur yang tidak memiliki data <em>core</em>.</p>