Влияние продолжительности контакта и глубины индентирования на адгезионную прочность: эксперимент и численное моделирование

The adhesive contact between a steel spherical indenter and a layer of transparent soft rubber fixed on a glass substrate is experimentally investigated. Obtained experimental results are compared with theory and numerical simulation, which demonstrates satisfactory agreement between these three approaches. The influence of the indenter time in the contact and the indentation depth on the value of the adhesive strength of the contact is studied. The features of experiments conducted under conditions of controlled displacement (fixed grips) and controlled force (fixed load) are discussed.

Perencanaan Dan Pembuatan Rangkaian Daya Starting Motor 3 Fasa ,380 Volt ,50 Hz, 3 Hp Dengan Metoda Bintang (Y) – Segitiga (∆)

Abstrak— Rangkaian daya untuk motor induksi 3 fasa, 380V, 50Hz, 3HP dengan metoda bintang-segitiga merupakan rangkaian yang digunakan untuk menyalurkan daya pada motor listrik. Permasalahannya adalah untuk mengendalikan motor induksi diperlukannya rangkaian daya, dimana starting awal motor memberikan dampak arus yang besar. Tujuan penelitian ini adalah untuk dapat melakukan starting pada motor 3 fasa dengan metoda bintang(Y) – segitiga(∆), Sebagai evaluasi dibuatnya suatu rangkaian daya metoda bintang segitiga, dimana hubung bintang digunakan untuk mengurangi arus starting yang besar, serta hubung segitiga digunakan untuk menstabilkan arus motor menjadi arus nominal sesuai nameplate motor. Hasil akhir menunjukkan bahwa untuk membuat panel distribusi terlebih dahulu yang dilakukan yaitu membuat perencanaan yang meliputi, perhitungan beban yang terpasang, pemilihan MCB sesuai dengan beban, pemilihan luas penampang sesuai dengan beban dan jenis kabel. Dimana dinyatakan dari sumber jala-jala 3 fasa, 380V yang dialirkan ke dalam rangkain daya untuk kendali motor 3 fasa, 380V, 3 HP, 50Hz metoda bintang-segitiga, diketahui bahwa beban yang terpasang 3 HP, arus pada hubung bintangnya 7,36 A, arus segitiga ataupun arus pada beban 4,26A , MCB yang dipakai memiliki kapasitas 17,04A, serta luas penampangnya 4,8 mm2 dengan jenis kabel NYM. Kata kunci: Rangkaian Daya, Motor 3 Fasa, Metoda Bintang – Segitiga Abstract— Power circuit for induction motor 3 Phase, 380 V,50 Hz, using star (Y) – triangle (∆) method is the circuit that is used to supply power to electric motor. The problem is to control an induction motor power is needed, and the first motor gives a big current impact. The objective of this study is to do the starting to 3 phase motor using star (Y) – triangle (∆) method where the star connection is used to stabilize the motor current into nominal current subject to the motor nameplate. The final finding indicates that before making a panel of distribution a planning must be prepared first, including couting the fixed load, choosing MCB subject to the load, choosing area of cross section subject tp load and type of cable. From the source of network of 3 phase, 380 V supplied to power circuit for the motor control of 3 phase, 380 V, 3HP, 50 Hz, with the star-triangle method, it is found out that the fixed load is 3HP, the current on the star connection is 7.36 A, current of triangle or current of load 4.26 A, the used MCB is with capacity 17.04 A and the area of cross section is 4.8 mm2 with type of cable NYM. Keywords: Power circuit, 3 Phase Motor, Star-Triangle Method

Performance Analysis of Photovoltaic Water Heating System

Performance of solar photovoltaic water heating systems with direct coupling of PV array to DC resistive heating elements has been studied and compared with solar photothermal systems. An analysis of optimum fixed load resistance for different climate conditions has been performed for simple PV heating systems. The optimum value of the fixed load resistance depends on the climate, especially on annual solar irradiation level. Use of maximum power point tracking compared to fixed optimized load resistance increases the annual yield by 20 to 35%. While total annual efficiency of the PV water heating systems in Europe ranges from 10% for PV systems without MPP tracking up to 15% for system with advanced MPP trackers, the efficiency of solar photothermal system for identical hot water load and climate conditions is more than 3 times higher.

Opportunities for near zero volt storage of lithium ion batteries

There are inherent safety risks associated with inactive lithium ion batteries leading to greater restrictions and regulations on shipping and inactive storage. Near zero volt storage under fixed load of all cells in a lithium ion battery is a promising approach to reduce or mitigate these safety risks in a highly controllable manner.