Mathematical programming model for heat exchanger design through optimization of partial objectives

Mathematical programming can be used for the optimal design of shell-and-tube heat exchangers (STHEs). This paper proposes a mixed integer non-linear programming (MINLP) model for the design of STHEs, following rigorously the standards of the Tubular Exchanger Manufacturers Association (TEMA). Bell–Delaware Method is used for the shell-side calculations. This approach produces a large and non-convex model that cannot be solved to global optimality with the current state of the art solvers. Notwithstanding, it is proposed to perform a sequential optimization approach of partial objective targets through the division of the problem into sets of related equations that are easier to solve. For each one of these problems a heuristic objective function is selected based on the physical behavior of the problem. The global optimal solution of the original problem cannot be ensured even in the case in which each of the sub-problems is solved to global optimality, but at least a very good solution is always guaranteed. Three cases extracted from the literature were studied. The results showed that in all cases the values obtained using the proposed MINLP model containing multiple objective functions improved the values presented in the literature.

Three-dimensional planar model estimation using multi-constraint knowledge based on k-means and RANSAC

Plane model extraction from three-dimensional point clouds is a necessary step in many different applications such as planar object reconstruction, indoor mapping and indoor localization. Different RANdom SAmple Consensus (RANSAC)-based methods have been proposed for this purpose in recent years. In this study, we propose a novel method-based on RANSAC called Multiplane Model Estimation, which can estimate multiple plane models simultaneously from a noisy point cloud using the knowledge extracted from a scene (or an object) in order to reconstruct it accurately. This method comprises two steps: first, it clusters the data into planar faces that preserve some constraints defined by knowledge related to the object (e.g., the angles between faces); and second, the models of the planes are estimated based on these data using a novel multi-constraint RANSAC. We performed experiments in the clustering and RANSAC stages, which showed that the proposed method performed better than state-of-the-art methods.

A three-stage DEA model to evaluate learning-teaching technical efficiency: Key performance indicators and contextual variables

This study evaluates the technical efficiency of the learning-teaching process in higher education using a three-stage procedure that offers advances in comparison to previous studies and improves the quality of the results. First, it utilizes a multiple stage Data Envelopment Analysis (DEA) with contextual variables. Second, the levels of super efficiency are calculated in order to prioritize the efficiency units. And finally, through sensitivity analysis, the contribution of each key performance indicator (KPI) is established with respect to the efficiency levels without omission of variables. The analytical data was collected from a survey completed by 633 tourism students during the 2011/12, 2012/13 and 2013/14 academic course years. The results suggest that level of satisfaction with the course, diversity of materials and satisfaction with the teacher were the most important factors affecting teaching performance. Furthermore, the effect of the contextual variables was found to be significant.

Development and verification of a three-dimensional numerical hydrodynamic, salinity, and temperature model of Chesapeake Bay.

Authors: B.H. Johnson, R.E. Heath, B.B. Hsieh, K.W. Kim, H.L. Butler.

User's guide for a three-dimensional numerical hydrodynamic, salinity, and temperature model of Chesapeake Bay /

Authors: Billy H. Johnson, Ronald E. Heath, Bernard B. Hsieh, Keu W. Kim, H. Lee Butler.

Three dimensional digital-computer model of the Ferron sandstone aquifer near Emery, Utah /

"October 1980."

A three region steam drum model for a nuclear power plant simulator (BRENDA) /

"Date published: August 1981."

Outlines of a plan for the establishment of an agricultural model school in the province of Munster : as recommended by the Irish Relief Committee in London of 1822, who appropriated three thousand pounds of their remaning funds, to aid in carrying this object into effect.

Includes "Appendix. Report of the Committee of the N.W. Society concerning an agricultural seminary" and "Extracts from Travels in Switzerland by S. Simond, respecting Mr. Fellenberg's establishment at Hofwyl."

Organizational maintenance repair parts and special tools list : air conditioning units, electric motor driven, 9,000 Btu/hr, vertical compact, 115 volt, single phase, 50/60 cycle (Therm-Air Manufacturing Co. model CV-9-1-15-60) FSN 4120-935-1609; 9,000 Btu/hr, vertical compact, 230 volt, three phase, 50/60 cycle ....

"February 1970."

Operator, organizational, direct support, general support and depot maintenance manual : air conditioning units, electric motor driven, 6,000 BTU/hr, vertical compact, 115 volt, single phase, 50/60 cycle (Thermo-Air model CV-6-1-15-60), FSN 4120-935-1608, 6,000 BTU/hr vertical compact, 208 volt, three phase, 400 cycle (Thermo-Air model CV-6-3-08-400), FSN 4120-935-1607.

Includes index.

Operator, organizational, direct support, general support, and depot maintenance manual : air conditioner, vertical, compact, 208 volts, A.C., 400 hertz, three phase, 18,000 BTU/hr cooling, 12,000 BTU/hr heating, (Keco model F18T4-2) FSN 4120-168-1775.

Includes index.

Operator's, organizational, direct support, and general support maintenance manual : air conditioner, horizontal, compact, 9,000 BTU/hr, 208 volt, three phase 50/60 hertz, model ECU-9HC326, NSN 4120-01-193-4998.

"27 March 1987."

Operator, organizational, direct support and general support maintenance manual : air conditioner, vertical compact, 6,000 BTU, 115 volts, single phase, 60 hertz (WEDJ model VM 6000-115) NSN 4120-00-935-1608 : air conditioner, vertical compact, 6,000 BTU, 208 volts, three phase, 400 hertz (WEDJ model VM 6000-208) NSN 4120-00-935-1607.

Includes index.

Organizational, direct support, and general support maintenance repair parts and special tools list (including depot maintenance repair parts and special tools) for air conditioner, vertical compact, 6,000 BTU, 115 volt, single phase, 50/60 Hz, Wedj model VM 6000-15, NSN 4120-00-935-1608 ... 208 volts, three phase, 400 Hz, Wedj model VM 6000-400, NSN 4120-00-935-1607.

Includes index.