Tomographic atom probe characterization of the microstructure of a cold worked 316 austenitic stainless steel after neutron irradiation

For the first time, chemical analyses using Atom Probe Tomography were performed on a bolt made of cold worked 316 austenitic stainless steel, extracted from the internal structures of a pressurized water reactor after 17 years of reactor service. The irradiation temperature of these samples was 633 K and the irradiation dose was estimated to 12 dpa (7.81 × 10²⁵ neutrons.m⁻², E > 1 MeV). The samples were analysed with a laser assisted tomographic atom probe. These analyses have shown that neutron irradiation has a strong effect on the intragranular distribution of solute atoms. A high number density (6 × 10²³ m⁻³) of Ni-Si enriched and Cr-Fe depleted clusters was detected after irradiation. Mo and P segregations at the interfaces of these clusters were also observed. Finally, Si enriched atmospheres were seen.     

Harmonic distortion-based island detection technique for inverter-based distributed generation

A harmonic distortion-based island detection technique for inverter-based distributed generation (IBDG) is proposed. The proposed technique is classified as an active island detection technique and it is based on the voltage change at the point of common coupling (PCC) that occurs in islanding. To avoid island detection failure in case of a close matching between IBDG-generated power and load power, an active power-voltage locus is introduced to shift the reference active power for PCC voltage change, therefore breaking the IBDG-load power balance and transferring the operating point outside the non-detection zone. A new harmonic performance index, named harmonic amplification factor, is introduced to detect the island. This factor amplifies each harmonic component by its order. Besides the ability of detecting short circuit, the proposed technique can discriminate between islanding and other disturbances, as load change, grid voltage distortion and unbalance, and capacitor bank switching. The proposed technique is validated by Matlab/Simulink simulation and practically as well.     

Optimal Water Resources Management: Case of Lower Litani River, Lebanon

The pressures of human population and patterns of development frequently jeopardize the integrity of river systems worldwide. An integrated approach to water resources management is essential, particularly in developing countries. This study presents the results of the water resources optimization conducted for the Lower Litani River Basin in Lebanon. The overall aim of the project is to develop, test, and critically evaluate an innovative approach to water resources management in the Mediterranean region. The method explores the ways in which multiple environmental, economic, and social benefits can be achieved through integrated management of water resources. The Water Resources Model was utilized to assess the efficiency of the baseline model scenario and for the optimization process of the different scenarios of the Litani Lower Basin. Strengths, weaknesses, opportunities and threats analysis was applied in order to derive the objectives and constraints. Results revealed that the potential retained scenarios aim at decreasing water consumption and demand, losses, and return flow. These scenarios mainly include the shift to drip irrigation, awareness campaigns, and losses control in domestic supply pipes. Other retained scenarios having a higher shortfall rely on the use of the Channel concrete lining to decrease losses and return flow, in addition to the awareness campaigns in both domestic and irrigation sectors, and less consumptive/more efficient irrigation methods such as sprinkler and drip irrigation at variable application percentages. Hence, most of the interventions or measures proposed are generally not costly and can be implemented.     

Threshold quantum secret sharing between multiparty and multiparty using Greenberger–Horne–Zeilinger state

We propose a (t, m)?(s, n) threshold quantum secret sharing protocol between multiparty (m members in group 1) and multiparty (n members in group 2) using a sequence of Greenberger–Horne–Zeilinger (GHZ) states, which is useful and efficient when the parties of communication are not all present. In the protocol, Alice prepares a sequence of GHZ states in one of the eight different states and sends the last two particles to the first agent while other members encode their information on the sequence via unitary transformations. Finally the last member in group 2 measures the qubits. It is shown that this scheme is safe.     

Thermally driven phase-change microactuation

This paper describes a microactuation scheme based on thermally driven liquid-vapor phase-change in a partially filled sealed cavity. A test structure for studying this system has been designed and fabricated. The cavity is 900 μm by 900 μm by 300 μm in size with a thin, 600 μm by 800 μm grid-shaped heater located on the floor of the cavity and elevated approximately 8 μm above it. The heater is composed of open diamond-shaped unit cells defined by 12-μm-wide, 3-μm-thick bulk-silicon beams, giving an overall electrical heater resistance of 3-10 Ω. Using methanol as the cavity fluid with partial filling, drive levels of 10 mW sustain a 1.2-Atm pressure rise within the cavity. Real-time measurements demonstrate a pressure response time on the order of 100 ms for an input power of 100 mW. Simulated pressure response calculations indicate the potential for an optimized response time on the order of 40 ms at this power level     

Removal of U(VI) from simulated liquid waste using synthetic organic resin

Poly(acrylic acid–dimethylaminoethyl methacrylate) was prepared by γ-radiation-induced copolymerization at a radiation dose of 60 kGy and a dose rate of 1.25 kGy h^–1. The resin obtained was used to remove U(VI) from simulated solution of the waste from the Fuel Manufacturing Pilot Plant (FMPP). A preliminary test of U(VI) adsorption onto the resin showed high affinity of this resin for U(VI) ions. The adsorption behavior toward the U(VI) ions was studied in relation to the contact time, pH, temperature, resin dosage, and initial concentration of metal ions. The adsorption isotherms of uranium onto the resin were described using the Langmuir and Freundlich models, with the Langmuir model being more adequate to the experimental equilibrium data. Without foreign ions, the maximum adsorption capacity of the resin for U(VI) was 105.7 mg g^–1. X-ray fluorescence was used to evaluate the amount of U(VI) ions on the resin sample before and after the adsorption.     

Orthonormal function parametrisation of model-predictive control for linear time-varying systems

It is well known that some practical difficulties are involved in the implementation of stabilising model predictive control for time-varying systems. In order to address the difficulty of computational load, this paper extends the orthonormal function method for model predictive control to linear time-varying systems. We provide sufficient conditions for a sub-optimal model predictive controller to be stabilising for a time-varying system. It is also shown that the orthonormal parametrisation method enables us to reduce the number of decision variables significantly and with a satisfactory performance. In addition, it is shown that orthonormality and, the called for, long prediction horizons are not necessary for stability. Examples are provided, illustrating the effectiveness of the method for linear time-varying systems.     

An accurate analytical I-V model for sub-90-nm MOSFETs and its application to read static noise margin modeling

We propose an accurate model to describe the I-V characteristics of a sub-90-nm metal-oxide-semiconductor field-effect transistor(MOSFET) in the linear and saturation regions for fast analytical calculation of the current.The model is based on the BSIM3v3 model.Instead of using constant threshold voltage and early voltage,as is assumed in the BSIM3v3 model,we define these voltages as functions of the gate-source voltage.The accuracy of the model is verified by comparison with HSPICE for the 90-,65-,45-,and 32-nm CMOS technologies.The model shows better accuracy than the nth-power and BSIM3v3 models.Then,we use the proposed I-V model to calculate the read static noise margin(SNM) of nano-scale conventional 6T static random-access memory(SRAM) cells with high accuracy.We calculate the read SNM by approximating the inverter transfer voltage characteristic of the cell in the regions where vertices of the maximum square of the butterfly curves are placed.The results for the SNM are also in excellent agreement with those of the HSPICE simulation for 90-,65-,45-,and 32-nm technologies.Verification in the presence of process variations and negative bias temperature instability(NBTI) shows that the model can accurately predict the minimum supply voltage required for a target yield.     

A new mathematical solution for predicting char activation reactions

The differential conservation equations that describe typical gas-solid reactions, such as activation of coal chars, yield a set of coupled second-order partial differential equations. The solution of these coupled equations by exact analytical methods is impossible. In addition, an approximate or exact solution only provides predictions for either reaction- or diffusion-controlling cases. A new mathematical solution, the quantize method (QM), was applied to predict the gasification rates of coal char when both chemical reaction and diffusion through the porous char are present. Carbon conversion rates predicted by the QM were in closer agreement with the experimental data than those predicted by the random pore model and the simple particle model.     

Filler-reduced phonon conductivity of thermoelectric skutterudites: Ab initio calculations and molecular dynamics simulations

The phonon conductivities of CoSb₃ and its Ba-filled structure Ba_x(CoSb₃)₄ are investigated using first-principle calculations and molecular dynamics (MD) simulations, along with the Green–Kubo theory. The effects of fillers on the reduction of the phonon conductivity of filled skutterudites are then explored. It is found that the coupling between filler and host is strong, with minor anharmonicity. The phonon density of states and its dispersion are significantly influenced by filler-induced softening of the host bonds (especially the short Sb–Sb bonds). Lattice dynamics and MD simulations show that, without a change in the host interatomic potentials, the filler–host bonding alone cannot lead to significant alteration of acoustic phonons or lowering of phonon conductivity. The observed smaller phonon conductivity of partially filled skutterudites is explained by treating it as a solid solution of the empty and fully filled structures.