Energy Loss and Radial Force Variation Caused by Impeller Trimming in a Double-Suction Centrifugal Pump

Impeller trimming is an economical method for broadening the range of application of a given pump, but it can destroy operational stability and efficiency. In this study, entropy production theory was utilized to analyze the variation of energy loss caused by impeller trimming based on computational fluid dynamics. Experiments and numerical simulations were conducted to investigate the energy loss and fluid-induced radial forces. The pump’s performance seriously deteriorated after impeller trimming, especially under overload conditions. Energy loss in the volute decreased after trimming under part-load conditions but increased under overload conditions, and this phenomenon made the pump head unable to be accurately predicted by empirical equations. With the help of entropy production theory, high-energy dissipation regions were mainly located in the volute discharge diffuser under overload conditions because of the flow separation and the mixing of the main flow and the stalled fluid. The increased incidence angle at the volute’s tongue after impeller trimming resulted in more serious flow separation and higher energy loss. Furthermore, the radial forces and their fluctuation amplitudes decreased under all the investigated conditions. The horizontal components of the radial forces in all cases were much higher than the vertical components.

Efektivitas Penggunaan Input Dalam Usaha Tani Bawang Merah Di Kecamatan Baraka Kabupaten Enrekang

The working pattern of shallot farmers in Enrekang Regency still adheres to the old model of production principles, were to increase production is accompanied by adding the inputs. In fact, in the dimension of the Cobb-Douglas production theory, the addition of inputs is not always necessary in line with the increase of production output. Therefore, this study aims to see the effectiveness of inputs in shallots farming in Enrekang Regency. The input variables used in this study include the area of land, capital, labor, and technology that are optimized and correlated with the production of shallots. The analytical method used is multiple linear regression by adopting the Cobb-Douglas production theory. The results of the analysis found that the use of inputs is reaching the condition of decreasing return to scale in shallots farming.

Reviewing Batik with Natural Coloring based on the Clean Production Theory with an Ecofeminist Perspective (Case Study: Putri Kawung Batik Community in Klaten)

Mass and rapid production of batik using synthetic color and printing techniques engenders environmental problems such as waste production, air pollution, water pollution, unhealthy and hazardous work environment, and a threat to the sustainability of hand-drawn batik. Clean production is one solution to this problem. This paper discusses the practice of batik with natural coloring based on the theory of clean production with an ecofeminist perspective. The method employed in this research is a case study with a one-unit production (cluster) approach of Putri Kawung batik community. The findings show that the practice of clean batik production in Putri Kawung batik community still focuses on the input and process of using natural coloring, material selection, and reuse of wax materials. This shows that the role of women through community gradually practices clean production, even though it has not yet extended to its output processing.

Theory of production in construction industry

In the absence of an explicit and specific theory, the management of production processes in construction is essentially based on a Taylorist view, based on the economic theory of production. Thus, given the particularities of construction, the plans developed are often unreal, with recurring delays and unforeseen circumstances during production. Thus, because of the importance and the latent need to develop a specific theory, this article uses a systematic literature review (SLR) to comprehend what has been developed and discuss the topic. The main objective is to answer the following research questions: 1) What is being proposed to develop a production theory applied to construction? 2) What is the approach used in the publications? 3) What can be proposed for the body of knowledge in question to fill gaps? Based on the results of the SLR, it was verified that the development of such a theory appears to be very incipient and not formalized in the publications, with inconclusive results and weak multidisciplinary cooperation. Furthermore, there are indications that authors associated with Lean Thinking may be leading research on production theory in construction since most of the publications have results that were conceptually based on Lean Construction principles. It is understood that the content of this article is relevant because it outlines the current stage of development of the theory and indicates possible paths to achievements.