Development of Thermochemical Heat Storage Based on CaO/CaCO3 Cycles: A Review

Due to the inconsistency and intermittence of solar energy, concentrated solar power (CSP) cannot stably transmit energy to the grid. Heat storage can maximize the availability of CSP plants. Especially, thermochemical heat storage (TCHS) based on CaO/CaCO3 cycles has broad application prospects due to many advantages, such as high heat storage density, high exothermic temperature, low energy loss, low material price, and good coupling with CSP plants. This paper provided a comprehensive outlook on the integrated system of CaO/CaCO3 heat storage, advanced reactor design, heat storage conditions, as well as the performance of CaO-based materials. The challenges and opportunities faced by current research were discussed, and suggestions for future research and development directions of CaO/CaCO3 heat storage were briefly put forward.

Macroeconomic Indicators as Potential Predictors of Construction Material Prices

The rate of construction materials is subjected to constant changes. The unexpected price changes affect the carrying-out rates of projects and even challenges the competence to finish the projects. The rapid and vast changes that occur all over the world in construction materials prices impacts the individual construction market value of each country. To avoid this problem, the contractor should have a tool or method that is capable to predict the future material prices. It is essential to predict the material prices variations during the implementation of the project as well as for preparing the tenders. Prediction of material price is an important function for effectively handling projects in terms of more exactly estimating, pursuing and monitoring projects. There are many tools that can help the construction contractors by its ability to accurately predict the future material price. Some of the methods normally used for prediction of materials prices are Artificial Neural Network, Fuzzy Logic, Statistical Method (includes regression analysis, MONTE CARLO method, ANOVA), and Trend Analysis. The type of predictors to these tools can be any factors that tend to have an impact on the prices of material. Macroeconomic indicators are one such factor that influences the prices of material as it reflects a country’s economic status. This is a pilot study conducted in India to determine the possible macroeconomic indicators that influence the building material prices namely Portland cement and steel. Keywords-Cost estimation, Artificial Neural Network, Macroeconomic indicator

Threshold Effect of Raw Material Prices on Economic Growth of African Countries

We study the nonlinear effects of raw material prices measured by that of cotton product on the economic growth of a sample of African countries for the period of 1991–2019. Using the procedure for determining endogenous thresholds (Hansen, 1999) [Threshold effects in non-dynamic panels: Estimation, testing, and inference. Journal of Econometrics, 93, 345–368], the study revealed that raw material prices positively affect economic growth when the prices reach a threshold above 96.1. These results indicate that to be effective, any economic policy measure aimed at accelerating the economic growth of these commodity-dependent countries must take into account the level of raw material price indices, the quality of governance and the level of financial development.

Solvothermal synthesis high lithium ionic conductivity of Gd-doped Li1.3 Al0.3Ti1.7(PO4)3 solid electrolyte

NASICON-type Li[Formula: see text]Al[Formula: see text]Ti[Formula: see text](PO[Formula: see text] (LATP) solid electrolytes have been widely studied because of its stability in the air, low material price and high ionic conductivity. Gd-doped Li[Formula: see text]Al[Formula: see text]Gd[Formula: see text]Ti[Formula: see text](PO[Formula: see text] ([Formula: see text]= 0, 0.025, 0.05, 0.075 and 0.1) with high ionic conductivity was successfully synthesized by solvothermal method for the first time in this work. The effect of Gd doping content on the structure and electrochemical performance of solid electrolytes was systematically studied. The optimal doping content of Gd is [Formula: see text]= 0.075. With the Gd doping content of 0.075, the solid electrolyte has the highest ionic conductivity of 4.23 × 10[Formula: see text] S cm[Formula: see text] at room temperature, the lowest activation energy of 0.247 eV and the highest relative density of 94.89%. This is because the fact that when [Formula: see text]= 0.075, it is the maximum content of Gd[Formula: see text] to replace Al[Formula: see text] and can completely enter the lattice of LATP, and does not emerge too much non-lithium ion conductive GdPO4 phase.

Suitable Material Selection for Large Size Cylindrical Gears*

Globalization and international supply chains constantly challenge gear- and steel manufacturers. In the case of large gear units in particular, expensive alloy contents have a direct impact on the material price. Steels with lower alloy contents and therefore cheaper steels are therefore becoming the focus of attention in order to further improve competitiveness. This article therefore compares two materials with different alloying elements and contents and thus different hardenability behaviour. For this purpose, extensive material characterizations as well as pulsator tests were carried out on case-hardened large gears. The aim of these tests was to determine the tooth root load-bearing capacity of the two material variants. Finally, the results are compared, discussed and recommendations for industrial application are derived, taking into account the hardenability of large gears. ◼

Parametric Cost Modelling for Investment Casting

This paper presents a parametric cost model for estimating the raw material cost of components realized employing the investment casting process. The model is built using sensitivity analysis and regression methods on data generated by an analytic cost model previously developed and validated by the same authors. This is the first attempt of developing a parametric cost model for investment casting based on activity-based costing. The proposed cost model accounts component volume, material density and material price. The error in estimating the raw material cost for components whose volume is within the common range of investment casting is around 11%.

Modifikasi Design Heatsink dan Dudukan Peltier pada Alat Transportasi Ikan Segar

Alat transportasi ikan segar (ALTIS) adalah sarana pendingin yang dapat mempertahankan mutu ikan segar. ALTIS umumnya digunakan oleh pedagang kelliling dalam transportasi dan distribusi produknya. Komponen yang menentukan kinerja pendingin adalah heatsink dan dudukan peltier. Kedua bagian ini berfungsi dalam transfer panas kotak penyimpanan ikan menuju udara. Namun, biaya produksi dan harga material kedua komponen tersebut cukup tinggi. Penelitian ini bertujuan untuk modifikasi spesifikasi heatsink dan dudukan peltier, agar mendapatkan efisiensi biaya pembuatannya. Heatsink dibuat dari 3 mm plat tembaga dengan 18 sirip aluminium yang memiliki ketinggian 10 mm dan ketebalan 1 mm. Sementara itu, dudukan peltier juga dibuat dari alumunium dengan ketebalan bervariasi (4, 5, 6, dan 10 mm). Performa kedua bagian ini diuji dengan variabel suhu heatsink dalam, heatsink luar, dan ruang penyimpanan ikan, setiap 5 menit selama 95 menit. Hasil pengujian menunjukkan bahwa suhu ruang penyimpanan ikan menggunakan heatsink baru (17,8°C) lebih rendah dari heatsink sebelumnya (18,3°C). Desain heatsink yang baru ini dapat mengurangi biaya pembuatan sebesar Rp. 807.000,00. Dudukan elemen peltier dengan alumunium setebal 4 mm dapat mempercepat proses perpindahan panas dari ruang penyimpanan ikan menuju peltier. Modifikasi ini dapat diaplikasikan untuk menurunkan biaya dan meningkatkan performa ALTIS.ABSTRACTRefrigerated Fresh Fish Container (ALTIS) is a cooler equipment to maintain the quality of fresh fish. ALTIS is usually used by the itinerant fish traders to preserve their products in transportation and distribution. The components that determine the cooler performance are the heatsinks and the Peltier base plate. These components are responsible for transferring the heat from the fish container to the air. However, the production costs and material price for both components are expensive. This study aimed to reduce production costs by modifying the heatsink and Peltier base plate design specifications. The heatsink was made from 3 mm thickness copper and aluminum fins. The aluminum fins were 18 pieces in total, with 1.6 mm thickness and 10 mm height. Meanwhile, the Peltier base plate was also made from aluminum with varied thicknesses (4, 5, 6, and 10 mm). The performance of both parts was evaluated by temperature measurement in the inner heatsink, outer heatsink, and box container for every 5 minutes in 95 minutes. The results showed that the refrigerated container box temperature with the new heatsink (17.8°C) was lower than the existing heatsink (18.3°C). Moreover, the new heatsink design may reduce the production costs by Rp. 807,000.00. Furthermore, the Peltier base plate with a 4 mm thickness could accelerate the heat-dissipating of Peltier. Thus, the modification can be applied for ALTIS production with lower cost and better performance.

How Student Worksheets Based Metacognitive can Improve Learning Outcomes on Material Price Index and Inflation?

The purpose of this paper is to improve student learning outcomes. This study is a Research and Development (R&D) using the 4D model Thiagarajan which includes stages Define, Design, Develop, and Disseminate but the Disseminate stage is not carried out. The findings showed that the feasibility of the material, language, evaluation, and graphics of 87%, 85%, 85%, 87% with a very decent category. The average N-gain score got a score of 0.6 categorized as moderate and classical completeness of student learning outcomes is 90%. While the results of the responses of students get an average percentage of 90,4% categorized as very feasible. Improved learning outcomes can be obtained using MMPII worksheets which include metacognitive features namely planning, monitoring, and evaluating. This study uses limited trials that were conducted on 20 students of XI IPS class Kanjeng Sepuh Senior High School.