A note on bi-objective optimization for sustainable supply chain network design in omnichannel

PurposeThis paper aims to correct the existing mixed integer programming (MIP) model proposed by Yadav et al. (2019) [“Bi-objective optimization for sustainable supply chain network design in omnichannel.”, Journal of Manufacturing Technology Management, Vol. 30 No. 6, pp. 972–986].Design/methodology/approachThis paper first presents a counterexample to show that the existing MIP model is incorrect and then proposes an improved mixed integer linear programming (MILP) model for the considered problem. Last, a numerical experiment is conducted to test our improved MILP model.FindingsThis paper demonstrates that the formulations of the facility capacity constraints and the product flow balance constraints in the existing MIP model are incorrect and incomplete. Due to this reason, infeasible solutions could be identified as feasible ones by the existing MIP model. Hence, the optimal solution obtained with the existing MIP model could be infeasible. A counter-example is used to verify our observations. Computational results verify the effectiveness of our improved MILP model.Originality/valueThis paper gives a complete and correct formulation of the facility capacity constraints and the product flow balance constraints, and conducts other improvements on the existing MIP model. The improved MILP model can be easily implemented and would help companies to have more effective distribution networks under the omnichannel environment.

Characteristic Analysis and Experiment of a Flow Distribution Valve

The comprehensive characteristics of flow distribution valve in water system are analyzed. The flow balance valve can change the drag efficient according to the condition of system, and can measure the flowrate. The structure of the flow distribution valve is introduced, and the theoretical calculation formula for the regulating valve are derived. A rated flowrate from 10.65m3/h to 20.48m3/h are offered in the numerical work. Fluent CFX analyses show good behaviours: through the benefits of V-ball valve good linearity and regulation characteristics, when the valve throttling, the system flow can maintain a relatively stable state, it can be conducived to improve the measurement accuracy of the distribution valve. The experimental results show that the measure accuracy is less than 5.8%.

RANS modelling of a single wind turbine wake in the unstable surface layer

Unstable atmospheric conditions are often observed during the daytime over land and for significant periods offshore, and are hence relevant for wake studies. A simple k-ε RANS turbulence model for simulation of wind turbine wakes in the unstable surface layer is presented, which is based on Monin-Obukhov similarity theory (MOST). The turbulence model parametrizes buoyant production of turbulent kinetic energy (TKE) without the use of an active temperature equation, and flow balance is ensured throughout the domain by modifications of the turbulence transport equations. Large eddy simulations and experimental data from the literature are used for validation of the model.

Differences in Formation Mechanism of Static Pressure Circumferential Distribution of Centrifugal Compressor Under Different Operating Conditions

The casing-wall static pressure of the centrifugal compressor behaves the double-peak distribution in the circumference at small flow rates but the single-peak distribution at large flow rates. A previous study shows that the double-peak distribution is induced by the redistribution of impeller outlet flow rates. In this paper, by using the similar simplified method of directly imposing pressure boundary to the diffuser outlet, the original reason for the formation process difference of pressure distribution in the circumference at different operating conditions is further investigated. The results show that at large flow rates, under the combined action of the specific downstream pressure distribution and the flow performance of the compressor itself, alternating low/high velocity airflow zones similar to those at small flow rates cannot be established in the diffuser when the impeller outlet flow rates are redistributed. Therefore, the static pressure can only express the single-peak distribution in the circumference. In fact, whether the static pressure exhibits the double-peak or single-peak distribution in the circumference depends on whether the impeller outlet flow mutation can destroy the original flow balance. When the flow mutation is dominant, the double-peak distribution is created, whereas when the original flow balance is prevailing, the single-peak distribution is formed.

Assessing the Energy, Indoor Air Quality, and Moisture Performance for a Three-Story Building Using an Integrated Model, Part Two: Integrating the Indoor Air Quality, Moisture, and Thermal Comfort

In this paper, an integrated model that coupled CONTAM and WUFI was developed to assess the indoor air quality (IAQ), moisture, and thermal comfort performance. The coupling method of CONTAM and WUFI is described based on the exchange of airflow rate control variables as infiltration, natural and mechanical ventilation parameters between heat and moisture flow balance equations in WUFI and contaminant flow balances equations in CONTAM. To evaluate the predictions of the integrated model compared to single models of CONTAM and WUFI, four scenarios were used. These scenarios are airtight-fan off, airtight-fan on, leaky-fan off, and leaky-fan on, and were defined for a three-story house subjected to three different climate conditions of Montreal, Vancouver, and Miami. The measures of the simulated indoor CO2, PM2.5, and VOCs obtained by CONTAM; the simulated indoor relative humidity (RH), predicted percentage of dissatisfied (PPD), and predicted mean vote (PMV) obtained by WUFI; and those obtained by the integrated model are compared separately for all scenarios in Montreal, Vancouver, and Miami. Finally, the optimal scenarios are selected. The simulated results of the optimal scenarios with the integrated model method (−28.88% to 46.39%) are different from those obtained with the single models. This is due to the inability of the single models to correct the airflow variables.

A brief overview on valorization of industrial tomato by-products using the biorefinery cascade approach

The industrial processing of tomato leads to substantial amounts of residues, typically known as tomato pomace or by-products, which can represent as much as 10% by weight of fresh tomatoes. At present, these residues are either used as feedstock for animals or, in the worst case, disposed of in landfills. This represents a significant waste because tomato pomace contains high-value compounds like lycopene, a powerful antioxidant, cutin, which can be used as a starting material for biopolymers, and pectin, a gelling agent. This article presents an overview of technologies that valorize tomato by-products by recovering added-value compounds as well as generating fuel for energy production. These technologies include operations for extraction, separation, and exploitation of lycopene, cutin and pectin, as well as the processes for conversion of the solid residues to fuels. Data collected from the review has been used to develop a biorefinery scheme with the related mass flow balance, for a scenario involving the tomato supply chain of Regione Campania in Italy, using tomato by-products as feedstock.

A Markov process model of sizing the capacity of reserved storage yard in intermodal container terminal

The intermodal container terminal is an important node linking the routes of shipping and China Railway Express. This paper proposes a Markov process model to explore the optimal capacity of the reserved storage yard in the intermodal container terminal. The flow balance equations are formulated to calculate the steady-state probability. The total cost is taken as the performance measure. Numerical analysis manifests that the railway preference rate and the strategy with and without transfer obviously affect the optimum capacity of the reserved storage yard. Some useful insights for the management of the intermodal container terminal are discussed.