An enhanced linear regression-based building energy model (LRBEM+) for early design

The design community lacks simple, data-driven energy assessment tools to explore energy-efficient alternatives during the early stages of building design. A promising option is to utilize a whole building energy simulation engine (e.g. EnergyPlus) within a Monte Carlo simulation framework to develop a linear regression-based building energy model (LRBEM) that can predict idealized heating and cooling loads based on parameters relevant to early design. Previous work was limited to medium-sized US commercial office buildings with rectangular geometries. A key limitation is addressed in this paper by considering complex geometries. A reformulated model, LRBEM+, is developed and tested with a suite of building geometries that represent limiting cases. The resultant relative error between LRBEM+ and EnergyPlus is generally less than 10%. Furthermore, LRBEM+ correctly predicts the direction and magnitude of changes in heating and cooling loads in response to changes in the most influential early design parameters.     

Toughness in synthetic and biological multilayered systems

Toughness in hard biological tissues is associated with fibrous or lamellar structures that deflect or stop growing cracks. In some cases, such as nacreous shell, protein interlayers absorb much of the crack energy. In other tissues, such as tooth enamel, the toughness derives from the mineral microstructure, and the small amount of residual protein apparently has little effect. There have been a number of efforts to make tough synthetic materials using layered structures. In this work, freeform fabrication has been used to make layered structures with a view to introducing similar toughness into brittle materials. Results are presented for epoxy-glass composites with glass fabric interlayers, porous alumina back-filled with aluminium metal, and layered glass-ceramic/silver materials.     

An evolutionary algorithm to generate alternatives (EAGA) for engineering optimization problems

Typically for a real optimization problem, the optimal solution to a mathematical model of that real problem may not always be the ‘best’ solution when considering unmodeled or unquantified objectives during decision-making. Formal approaches to explore efficiently for good but maximally different alternative solutions have been established in the operations research literature, and have been shown to be valuable in identifying solutions that perform expectedly well with respect to modeled and unmodeled objectives. While the use of evolutionary algorithms (EAs) to solve real engineering optimization problems is becoming increasingly common, systematic alternatives-generation capabilities are not fully extended for EAs. This paper presents a new EA-based approach to generate alternatives (EAGA), and illustrates its applicability via two test problems. A realistic airline route network design problem was also solved and analyzed successfully using EAGA. The EAGA promises to be a flexible procedure for exploring alternative solutions that could assist when making decisions for real engineering optimization problems riddled with unmodeled or unquantified issues.     

A semi-analytical technique for bending analysis of cylindrical panels with general loading and boundary conditions

Cylindrical panels are structural elements widely used in engineering structures for high value of strength to weight ratio. Exact solutions of cylindrical panels are available only for a very limited number of cases. The main target of this paper is to utilize a semianalytical technique to study bending behavior of cylindrical panels with different boundary conditions under general distributed loading. The solution of the partial differential equations was reduced to an iterative sequential solution of a double set of ordinary differential equations using extended Kantorovich method. The competence and accuracy of the method is established by comparison with available results in the literature and finite element analyses which shows good agreement.     

Coupling of logistic regression analysis and local search methods for characterization of water distribution system contaminant source

Accidental or intentional drinking water contamination has long been and remains a major threat to water security throughout the world. An inverse problem can be constructed, given sensor measurements in a water distribution system (WDS), to identify the contaminant source characteristics by integrating a WDS simulation model with an optimization method. However, this approach requires numerous compute-intensive simulation runs to evaluate potential solutions; thus, determining the best source characteristic within a reasonable computational time is challenging. In this paper, we describe the development of a WDS contamination characterization algorithm by coupling a statistical model with a heuristic search method. The statistical model is used to identify potential source locations of contamination and a local search aims at further refining contaminant source characteristics. Application of the proposed approach to two illustrative example water distribution networks demonstrates its capability of adaptively discovering contaminant source characteristics as well as evaluating the degree of non-uniqueness of solutions. The results also showed that the local search as an optimizer has better performance than a standard evolutionary algorithm (EA).     

Effects of chemical structure of phenolic antioxidants on Ziegler–Natta catalyst performance during propylene polymerization

Present work studied the synthesis of in-reactor stabilization of polypropylene via introducing antioxidant into polymerization media. Special attention was dedicated to assess the efficiency of antioxidant in catalyst deactivation. Three different types of antioxidants (Irganox 1076, Irganox 1010 and Irganox 1330) which contain ester and/or phenolic OH functional groups were chosen to investigate their impact on Ziegler–Natta catalyst performance during slurry propylene polymerization. Our Results indicated that not only phenolic OH groups but also esteric bond of antioxidants are capable of interacting with active center of catalyst and consequently decreasing the catalyst activity. Our propylene polymerization results showed that determining factors such as antioxidant chemical structures and its steric hindrance effect and the number of functional groups (phenolic and esteric groups) affected on the Ziegler–Natta catalyst performance. Therefore, effects of these three types of antioxidants on polymer characteristics such as particle size distribution, morphology, T _m , T _c , X _c , and isotacticity were evaluated. Morphological analysis using scanning electron microscopy (SEM) showed that introducing antioxidant during propylene polymerization did not destroy the spherical morphology of the polypropylene particles. Conclusively, due to the negative effect of esteric bond of antioxidant on Ziegler–Natta catalyst performance, the use of antioxidant without ester groups (Irganox 1330) is more recommended during propylene polymerization.     

Life-Cycle-based Solid Waste Management. I: Model Development

This paper describes an integrated solid waste management (ISWM) model to assist in identifying alternative SWM strategies that meet cost, energy, and environmental emissions objectives. An SWM system consisting of over 40 unit processes for collection, transfer, separation, treatment (e.g., combustion, composting), and disposal of waste as well as remanufacturing facilities for processing recycled material is defined. Waste is categorized into 48 items and their generation rates are defined for three types of sectors: single-family dwelling, multifamily dwelling, and commercial. The mass flow of each item through all possible combinations of unit processes is represented in a linear programming model using a unique modeling approach. Cost, energy consumption, and environmental emissions associated with waste processing at each unit process are computed in a set of specially implemented unit process models. A life-cycle approach is used to compute energy consumption and emissions of CO, fossil- and biomass-derived CO2,NOx,SOx, particulate matter, PM10 and greenhouse gases. The model is flexible to allow representation of site-specific issues, including waste diversion targets, mass flow restrictions and requirements, and targets for the values of cost, energy, and each emission. A companion paper describes the application of this model to examine several SWM scenarios for a hypothetical, but realistic, case study.     

Effect of graphene oxide on the interlaminar fracture toughness of carbon fiber/epoxy composites

Graphene oxide (GO) nanoparticles were introduced in the interlaminar region of carbon fiber–epoxy composites by dispersing it in a thermoplastic polymer carrier such as polyvinylpyrrolidone (PVP). Mode‐I fracture toughness (G_IC) was investigated using double cantilever beam testing to evaluate the effect of the GO on the delamination behavior of the composite. The GO content was varied from 0% to 7% by weight as a function of the PVP content. Improvement of ～100% in the Mode I fracture toughness (G_IC) was observed compared to composites with no GO. The optimum amount of nanoparticles for improving the interlaminar fracture toughness was found to be ～0.007% by weight of the composite. The increase in the value of flexural strength value was also observed. Scanning electron microscopy of fracture surfaces, X‐ray diffraction, and transmission electron microscopy, and reflectance Fourier transform infrared spectra, as well as Raman spectroscopy results, are presented to support the conclusions. POLYM. ENG. SCI., 59:1199–1208 2019. © 2019 Society of Plastics Engineers     

Study on propylene polymerization in the presence of phenolic antioxidant (Irganox 1076) and characterization of stabilized polymers

The aim of this study was to investigate different concentrations of Irganox 1076 on Ziegler–Natta catalyst performance during propylene polymerization. Antioxidant masking was conducted by addition of different molar ratio of triethylaluminum (TEAL). Proton nuclear magnetic resonance and Fourier transform infrared spectroscopy spectra confirmed the complete conversion of antioxidant to aluminum aryloxide form. The different concentrations of masked antioxidant with different molar ratio of TEAL were used during polymerization and the catalyst activity was evaluated. Morphology, particle size distribution, melt temperature, crystallization temperature, degree of crystallinity, oxidative induction time, and isotacticity of products in the presence of masked antioxidant were evaluated. Results showed that incomplete masking of OH phenolic antioxidant led to significant catalyst activity reduction. J. VINYL ADDIT. TECHNOL., 21:285–289, 2015. © 2014 Society of Plastics Engineers     

Decision Support Tool for Life-Cycle-Based Solid Waste Management

Existing solid waste management (SWM) planning software provides only limited assistance to decision makers struggling to find strategies that address their multifarious concerns. The combinatorial nature (many waste items and many management options) and multiple objectives of the SWM problem severely constrain the effectiveness of a manual search process using these tools. Recognizing this, researchers have proposed several optimization-based search procedures. These methods, however, enjoy limited use due to the substantial expertise required for their application. This paper presents a new computer-based decision support framework that addresses these limitations. The new framework integrates process models that quantify the life-cycle inventory of a range of pollutants and costs for an extensive municipal solid waste system, an optimization search procedure that identifies strategies that meet cost and environmental objectives and site-specific restrictions, and a user-friendly interface that facilitates utilization of these components by practitioners. After describing the software design, the use and value of the tool in typical waste management scenarios is demonstrated through a hypothetical, but realistic, case study in which several alternative SWM strategies are generated and examined.