Alexander W.

Eloquent, Laravel’s ORM, is a powerful tool for interacting with relational databases. It models entity relationships such as one-to-many and many-to-many, but production applications often need to produce very specific data structures that cannot be directly generated from Eloquent built-in methods. Instead of looping through collections to wrangle your query results, it is possible to extend Laravel’s basic relation classes and implement custom relations that you can easily reuse within and… Show more

Eloquent, Laravel’s ORM, is a powerful tool for interacting with relational databases. It models entity relationships such as one-to-many and many-to-many, but production applications often need to produce very specific data structures that cannot be directly generated from Eloquent built-in methods. Instead of looping through collections to wrangle your query results, it is possible to extend Laravel’s basic relation classes and implement custom relations that you can easily reuse within and among Laravel projects. You will dive into the guts of Eloquent and emerge an effective power user. Show less

PHP owes its appeal and popularity to its low barriers to entry. Anyone with access to a basic LAMP stack can get started in just a few hours, but if you want to write a production-level application, you need the right tools. The PHP community today relies heavily on Composer and PHPUnit as tools and PSRs as the common dialect. npm is the unavoidable front-end counterpart to Composer. Git, though not specific to PHP, is critical to developing a maintainable project. This talk will guide you… Show more

PHP owes its appeal and popularity to its low barriers to entry. Anyone with access to a basic LAMP stack can get started in just a few hours, but if you want to write a production-level application, you need the right tools. The PHP community today relies heavily on Composer and PHPUnit as tools and PSRs as the common dialect. npm is the unavoidable front-end counterpart to Composer. Git, though not specific to PHP, is critical to developing a maintainable project. This talk will guide you through these topics so you have a basic understanding of the modern PHP developer’s toolbox. Show less

Citations are commonly held to represent scientific impact. To date, however, there is no empirical evidence in support of this postulate that is central to research assessment exercises and Science of Science studies. Here, we report on the first empirical verification of the degree to which citation numbers represent scientific impact as it is actually perceived by experts in their respective field. We run a large-scale survey of about 2000 corresponding authors who performed a pairwise… Show more

Citations are commonly held to represent scientific impact. To date, however, there is no empirical evidence in support of this postulate that is central to research assessment exercises and Science of Science studies. Here, we report on the first empirical verification of the degree to which citation numbers represent scientific impact as it is actually perceived by experts in their respective field. We run a large-scale survey of about 2000 corresponding authors who performed a pairwise impact assessment task across more than 20000 scientific articles. Results of the survey show that citation data and perceived impact do not align well, unless one properly accounts for strong psychological biases that affect the opinions of experts with respect to their own papers vs. those of others. First, researchers tend to largely prefer their own publications to the most cited papers in their field of research. Second, there is only a mild positive correlation between the number of citations of top-cited papers in given research areas and expert preference in pairwise comparisons. This also applies to pairs of papers with several orders of magnitude differences in their total number of accumulated citations. However, when researchers were asked to choose among pairs of their own papers, thus eliminating the bias favouring one's own papers over those of others, they did systematically prefer the most cited article. We conclude that, when scientists have full information and are making unbiased choices, expert opinion on impact is congruent with citation numbers. Show less

Manufacturing is an energy-intensive process which could account for significant energy consumption worldwide. Reducing energy consumption on a product level, in addition to a process or facility level, is being seen as a more worthwhile endeavor in light of rising energy costs and environmental concerns. To accomplish this, it is necessary to consider the role of product design in energy consumption. It is possible to design a product such that its manufacture consumes less energy.… Show more

Manufacturing is an energy-intensive process which could account for significant energy consumption worldwide. Reducing energy consumption on a product level, in addition to a process or facility level, is being seen as a more worthwhile endeavor in light of rising energy costs and environmental concerns. To accomplish this, it is necessary to consider the role of product design in energy consumption. It is possible to design a product such that its manufacture consumes less energy. However, this requires a good model of energy consumption based on the design parameters. A good model must be detailed enough to yield accurate results, but at the same time simple enough such that it can be applied easily and consistently in day-to-day design work. In this paper, we propose an approach for generating such a model by decomposing the manufacturing process into its energy-consuming components. For each component, the relevant design and manufacturing parameters can be elicited by performing sensitivity analysis through analysis and experimentation. Parameters which do not greatly contribute to variance in energy consumption can be held constant, thus simplifying the model. Thus, the simplest possible model can be derived for a specified level of accuracy. We illustrate that critical parameters from energy point of view can differ greatly from process to process by investigating representative manufacturing processes in four general categories: additive, subtractive, forming, and solidification. Finally, we present a case study for injection molding. Show less

The development of product design specifications (PDS) is an important part of the product development process. Incompleteness, ambiguity, or inconsistency in the PDS can lead to problems during the design process and may require unnecessary design iterations. This generally results in increased design time and cost. Currently, in many organizations, PDS are written using word processors. Since documents written by different authors can be inconsistent in style and word choice, it is difficult… Show more

The development of product design specifications (PDS) is an important part of the product development process. Incompleteness, ambiguity, or inconsistency in the PDS can lead to problems during the design process and may require unnecessary design iterations. This generally results in increased design time and cost. Currently, in many organizations, PDS are written using word processors. Since documents written by different authors can be inconsistent in style and word choice, it is difficult to automatically search for specific requirements. Moreover, this approach does not allow the possibility of automated design verification and validation against the design requirements and specifications. In this paper, we present a computational framework and a software tool based on this framework for writing, annotating, and searching computer-interpretable PDS. Our approach allows authors to write requirement statements in natural language to be consistent with the existing authoring practice. However, using mathematical expressions, keywords from predefined taxonomies, and other metadata the author of PDS can then annotate different parts of the requirement statements. This approach provides unambiguous meaning to the information contained in PDS, and helps to eliminate mistakes later in the process when designers must interpret requirements. Our approach also enables users to construct a new PDS document from the results of the search for requirements of similar devices and in similar contexts. This capability speeds up the process of creating PDS and helps authors write more detailed documents by utilizing previous, well written PDS documents. Our approach also enables checking for internal inconsistencies in the requirement statements. Show less

Chapter 31: Towards Energy-Efficient Manufacturing Enterprises

Industrial enterprises have significant negative impacts on the global environment. Collectively, from greenhouse gases to energy consumption to solid waste, they are the single largest contributor to a growing number of planet-threatening environmental problems. For example, according to the Department of Energy’s Energy Information Administration, the industrial sector consumes 31% of the total energy and the… Show more

Chapter 31: Towards Energy-Efficient Manufacturing Enterprises

Industrial enterprises have significant negative impacts on the global environment. Collectively, from greenhouse gases to energy consumption to solid waste, they are the single largest contributor to a growing number of planet-threatening environmental problems. For example, according to the Department of Energy’s Energy Information Administration, the industrial sector consumes 31% of the total energy and the transportation sector consumes 28% of the energy. Considering that a large portion of the transportation energy costs are involved in moving manufactured goods, the energy consumption of the industrial sector could reach nearly 45% of the total energy costs. Hence, it is very important to improve the energy efficiency of our manufacturing enterprises. In this chapter, we outline several different strategies for improving the energy efficiency in manufacturing enterprises. These include reducing energy consumption at the process level, reducing energy consumption at the facilities level, and improving the efficiency of the energy generation and conversion process. The main focus of this chapter is on process level energy efficiency. We present several case studies to illustrate different strategies. Show less

Today's ubiquitous use of plastics in product design and manufacturing presents significant environmental and human health challenges. Injection molding, one of the most commonly used processes for making plastic products, consumes a significant amount of energy. A methodology for accurately estimating the energy consumed to injection-mold a part would enable environmentally conscious decision making during the product design. Unfortunately, only limited information is available at the design… Show more

Today's ubiquitous use of plastics in product design and manufacturing presents significant environmental and human health challenges. Injection molding, one of the most commonly used processes for making plastic products, consumes a significant amount of energy. A methodology for accurately estimating the energy consumed to injection-mold a part would enable environmentally conscious decision making during the product design. Unfortunately, only limited information is available at the design stage. Therefore, accurately estimating energy consumption before the part has gone into production can be challenging. In this paper, we describe a methodology for energy estimation that works with the limited amount of data available during the design stage, namely the CAD model of the part, the material name, and the production requirements. The methodology uses this data to estimate the parameters of the runner system and an appropriately sized molding machine. It then uses these estimates to compute the machine setup time and the cycle time required for the injection molding operation. This is done by appropriately abstracting information available from the mold flow simulation tools and analytical models that are traditionally used during the manufacturing stage. These times are then multiplied by the power consumed by the appropriately sized machine during each stage of the molding cycle to compute the estimated energy consumption per part. Show less

As collaborative efforts in electro-mechanical design have scaled to large, distributed groups working for years on a single product, an increasingly large gulf has developed between the original stated goals of the project and the final design solution. It has thus become necessary to validate the final design solution against a set of requirements to ensure that these goals have, in fact, been met. This process has become tedious for complex products with hundreds of design aspects and… Show more

As collaborative efforts in electro-mechanical design have scaled to large, distributed groups working for years on a single product, an increasingly large gulf has developed between the original stated goals of the project and the final design solution. It has thus become necessary to validate the final design solution against a set of requirements to ensure that these goals have, in fact, been met. This process has become tedious for complex products with hundreds of design aspects and requirements. By formalizing the representation of requirements and the design solution, tools can be developed to a large extent automatically perform this validation. In this paper, we propose a formal approach for relating product requirements to the design solution. First, we present a formal model for representing product requirements. Then, we introduce the Core Product Model (CPM) and the Open Assembly Model (OAM) for representing the design solution. Finally, we link these models formally and provide an example with an actual consumer device. Show less