fridges are used in various industries, and heat exchanger is one of the main components of these systems; therefore, efficiency analysis of these systems is very important. in many fridges, frost over the heat exchanger tubes or pipes affects the system operation and reduces heat transfer between the refrigerant and ambient, so defrosting systems are usually used to enhance heat transfer. desi...

The dynamics of an open quantum system can be described by a quantum operation: A linear, complete positive map of operators. Here, I exhibit a compact expression for the time reversal of a quantum operation, which is closely analogous to the time reversal of a classical Markov transition matrix. Since open quantum dynamics are stochastic, and not, in general, deterministic, the time reversal i...

We analyze the implementation of the time-reversal (TR) transformation in the algebraic approach to tetrahedral local molecules through the chain of groups U(5) ⊃ U(4) ⊃ K(4) = A(4) ∧ S(4) ⊃ S(4) ≈ Td. We determine the general form of the TR operation using a purely algebraic realization, based exclusively on the requirement that the irreducible representations must not be changed under the tim...

Microgrid (MG) systems effectively integrate a generation mix of solar, wind, and other renewable energy resources. The intermittent nature resources the unpredictable weather conditions contribute largely to unreliability microgrid real-time operation. This paper investigates behavior for different scenarios photovoltaic in real-time. Reactive power coordination control load shedding mechanism...

after springs production, different residual stresses are created in the inner and outer surfaces of spring wires. some of these stresses for example compressive residual stresses are useful and some are harmful. the effects of vareation of these stresses are caused spring relaxation and decrising in their free length when they are loaded intermittently. for review this phenomena in this resear...

The IEEE 1588 precision time protocol (PTP) time-setting mode of operation can be used to dramatically improve the quality of time-based systems that rely on a physical layer syntonization source in addition to PTP. Based on the standardized PTP protocol and common network frequency distribution techniques, the PTP time-setting mode of operation is capable of distributing time over packet-based...

background: surgical technique using small-diameter  instruments and single-incision laparoscopy are two new options for less invasive laparoscopic cholecystectomy (lc). in this study, we have compared mini-lc (mlc) with single-incision lc (silc). materials and methods: this study is a randomized clinical trial conducted on the patients diagnosed with  symptomatic cholelithiasis who underwent l...