This paper proposes a 2.4 GHz active mixer without passive inductor for the transceiver system. Taking into account the design requirements of the mixer, a double-balanced down-conversion structure with active inductor and negative resistance is designed. The proposed mixer with 130 nm CMOS technology is designed and simulated using Cadence software at 1.5 V supply voltage. Although we had to compromise conversion gain with linearity, we were able to achieve very High conversion gain with average linearity. Based on the results of post-layout simulations, the conversion gain of 27.57 dB, IIP3 equal to -7.88 dBm, 1-dB compression point equal to -17.34 dBm and IIP2 equal to 44.22 dBm with power consumption of 2.5 mW was obtained for the proposed mixer. The chip size without input and output pads is 95.18 µm × 117.68 µm, which leads to a chip area of 0.0112mm2.

Structural fire safety capacity of concrete is very complicated because concrete materials have considerable variations. In this paper, constitutive models and relationships for concrete subjected to fire are developed, which are intended to provide efficient modeling and to specific fire-performance criteria of the behavior of concrete structures exposed to fire. They are developed for unconfined concrete specimens that include residual compressive and tensile strengths, compressive elastic modulus, compressive and tensile stress-strain relationships at elevated Temperatures. In this paper, the proposed relationships at elevated Temperatures are compared with experimental result tests and pervious existing models. It affords to find several advantages and drawbacks of present stress-strain relationships and using these results to establish more accurate and general compressive and tensile stress-strain relationships. Additional experimental test results are needed in tension and the other main parameters at elevated Temperatures to establish well-founded models and to improve the proposed relationships. The developed models and relationships are general, rational, and have good agreement with experimental data.

Intensive study of the High Temperature superconductors has been ongoing for two decades. A great deal of this effort has been devoted to the underdoped regime, where the new and difficult physics of the doped Mott insulator has met   extra complications including bilayer coupling/splitting, shadow bands, and hot spots. While these complications continue to unfold, in this short overview the focus is moved to the region of actual High-Tc, that of optimal doping. The focus here also is not on the superconducting state itself, but primarily on the characteristics of the normal state from which the superconducting instability arises, and even these can be given only a broad-brush description. A reminder is given of two issues: (i) why the “optimal Tc” varies: for n-layered systems it increases for n up to 3, then decreases; for a given n, Tc increases according to the ‘basis’ atom in the order Bi, Tl, Hg; (ii) how does pressure, or a particular uniaxial strain, increase Tc when the zero-strain system is already optimally doped?

As worldwide demand of hydrocarbon is growing fast, the oil and gas companies have been forced to explore reservoirs with more hostile conditions, such as High-pressure, High-Temperature conditions. Improved technology, material selection and testing procedures are required to overcome the common problems in these conditions. One of the main phases of well construction is cementing job. Appropriate selection of cementing material can guarantee a successful cementing job. Many researchers investigated the required cement properties for applications in High-pressure, HighTemperature conditions. However, the focus of their work was on the mechanical properties of set cement, while the other properties have not been studied enough. The purpose of this work is to produce a High resistant cement system, which can satisfy the other essential requirements at the same time. The main other requirements include free fluid content, thickening time and expansion capability, which have been investigated in this work. The results show that although some cement systems have High mechanical resistant, but their application is limited due to undesirable values of other properties. Therefore, different additives have been used to adjust the properties of the final cement system. The High-resistant cement is produced by adding siliceous material. Free fluid content, thickening time and expansion capability of the High-resistant cements are adjusted by adding polyvinyl alcohol, lignosulfonate and MgO, respectively. The combined effect of these additives is investigated to develop a High-resistant system, which has optimum values of other essential properties too.

Dual phase steels with different martensite volume fraction and morphology were tensile tested at a Temperature range of 25 to 550°C. Stress-strain incurves of all steels showed serration flow at Temperatures of 250 and 350°C, and smooth flow at the other Temperatures. Both yield and ultimate tensile strengths increased with increasing testing Temperature up to about 450°C and then decreased at Higher Temperatures. At a given Temperature, yield stress, tensile strength, and work hardening increased with increasing volume fraction of martensite. Similar behavior was observed by changing martensite morphology from network to fibrous martensite. The change in mechanical properties Was related to the effects of dynamic strain aging, High Temperature softening, and martensite tempering.