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Massive infiltration of photovoltaic (PV) systems into electric supply networks creates numerous challenges in the present era, as the PV systems become an alternative to non-renewable energy resources. Partial shading, nevertheless, is an essential problem which affects the productivity and life of PV plants. PV reconfiguration is known as a powerful technique to resolve this effect. It is achieved by rearranging the PV modules according to their temperature and levels of shade. Therefore, in this paper, we have utilized three simple population-based optimization algorithms that are known as the flow regime algorithm (FRA), the social mimic optimization algorithm (SMO), and the Rao optimization algorithm to dynamically restructure the PV array. The effectiveness of the proposed algorithms is evaluated using several metrics such as fill factor, mismatch losses, percentage of power loss, and percentage of power enhancement. Besides, the results obtained are compared with a regular total-cross-tied (TCT) connection and recently published techniques such as the competence square (CS) and genetic algorithm (GA). Furthermore, to demonstrate the suitability of proposed approaches in real-time implementation, real-time irradiation data of a particular location are considered and fed into the proposed algorithms for effective shade dispersion. After successful shade dispersion, the total energy generated using the three proposed algorithms is calculated and compared with the TCT reconfigured system for one year. The presented energy calculations and revenue generation confirm that the power produced by the proposed FRA technique is 13% higher than that generated by the TCT configuration. Furthermore, the presented PV characteristics show a reduced number of multiple peaks in the system. Thus, the proposed FRA technique can be endorsed as a technique that is superior to other existing methods.

First-principles methods are employed to determine the structural, mechanical and thermodynamic reasons for the experimentally reported cubic WN phase. The defect-free rocksalt phase is both mechanically and thermodynamically unstable, with a negative single crystal shear modulus C 44 = -86 GPa and a positive enthalpy of formation per formula unit H f = 0.623 eV with respect to molecular nitrogen and metallic W. In contrast, WN in the NbO phase is stable, with C 44 = 175 GPa and H f = -0.839 eV. A charge distribution analysis reveals that the application of shear strain along [100] in rocksalt WN results in an increased overlap of the t 2g orbitals which causes electron migration from the expanded to the shortened W-W <110> bond axes, yielding a negative shear modulus due to an energy reduction associated with new bonding states 8.1-8.7 eV below the Fermi-level. A corresponding shear strain in WN in the NbO-phase results in an energy increase and a positive shear modulus. The mechanical stability transition from the NaCl to the NbO phase is explored using supercell calculations of the NaCl structure containing C v = 0-25% cation and anion vacancies, while keeping the N-to-W ratio constant at unity. The structure is mechanically unstable for C v < 5%. At this critical vacancy concentration, the isotropic elastic modulus E of cubic WN is zero, but increases steeply to E = 445 GPa for C v = 10%, and then less steeply to E = 561 GPa for C v = 25%. Correspondingly, the hardness estimated using Tian's model increases from 0 to 15 to 26 GPa as C v increases from 5% to 10% to 25%, indicating that a relatively small vacancy concentration stabilizes the cubic WN phase and that the large variations in reported mechanical properties of WN can be attributed to relatively small changes in C v .

Patients undergoing anterior cervical fusion have diminished neck motion compared with normal volunteers. Following surgery, they may be expected to gain motion, even when undergoing multilevel fusions. However, these patients are unlikely to regain the neck motion seen among normal individuals without neck complaints.

NbN x layers were deposited by reactive magnetron sputtering on MgO(001) substrates in 0.67 Pa pure N 2 at T s = 600-1000 °C. T s ≥ 800 °C leads to epitaxial layers with a cube-on-cube relationship to the substrate: (001) NbN ||(001) MgO and [100] NbN ||[100] MgO. The layers are nearly stoichiometric with x = 0.95-0.98 for T s ≤ 800 °C, but become nitrogen deficient with x = 0.81 and 0.91 for T s = 900 and 1000 °C. Xray diffraction reciprocal space maps indicate a small in-plane compressive strain of-0.0008±0.0004 for epitaxial layers, and a relaxed lattice constant that decreases from 4.372 Å for x = 0.81 to 4.363 Å for x = 0.98. This unexpected trend is attributed to increasing Nb and decreasing N vacancy concentrations, as quantified by first-principles calculations of the lattice parameter vs point defect concentration, and consistent with the relatively small calculated formation energies for N and Nb vacancies of 1.00 and-0.67 eV at 0 K and-0.53 and 0.86 eV at 1073 K, respectively. The N-deficient NbN 0.81 (001) layer exhibits the highest crystalline quality with in-plane and out-of-plane x-ray coherence lengths of 4.5 and 13.8 nm, attributed to a high Nb-adatom diffusion on a N-deficient growth front. However, it also contains inclusions of hexagonal NbN grains which lead to a relatively high measured hardness H = 28.0±5.1 GPa and elastic modulus E = 406±70 GPa. In contrast, the nearly stoichiometric phase-pure epitaxial cubic NbN 0.98 (001) layer has a H = 17.8±0.7 GPa and E = 315±13 GPa. The latter value is slightly smaller than 335 and 361 GPa, the isotropic elastic modulus and the [100]-indentation modulus, respectively, predicted for NbN from the calculated c 11 = 641 GPa, c 12 = 140 GPa, and c 44 = 78 GPa. The electrical resistivity ranges from 171-437 μΩ-cm at room temperature and 155-646 μΩ-cm at 77 K, suggesting carrier localization due to disorder from vacancies and crystalline defects.

Epitaxial MoN x layers deposited on MgO(001) by reactive magnetron sputtering in 20 mTorr N 2 at T s = 600-1000 °C exhibit a cubic rock-salt type structure, a N-to-Mo ratio that decreases from x = 1.25-0.69 with increasing T s , and a lattice constant that simultaneously decreases from 4.26-4.16 Å. A combination of composition, thickness, lattice-constant, and atomic area-density measurements indicate that the rock-salt structure contains both anion and cation vacancies, with the Mo site occupancy Χ Mo decreasing from 0.89±0.06 to 0.70±0.04 while the N site occupancy Χ N increases from 0.60±0.04 to 0.88±0.04, as x increases from 0.69-1.25. Density functional calculations for over 200 cubic MoN x configurations confirm the energetic stability of both cation and anion vacancies and predict Χ Mo to decrease from 1.00 to 0.67 for x = 0.54-1.50, while Χ N increases from 0.50 to 1.00 for x = 0.50-1.36. The simulations are in good agreement with experiments and indicate a preference for a 75% site occupancy on both sublattices for compositions near stoichiometry, with Χ Mo = 0.75 for x = 1.00-1.22 and Χ N = 0.75 for x = 0.86-1.00. Correspondingly, cubic stoichiometric MoN is most stable in the NbO structure.

First-principle density-functional calculations coupled with the USPEX evolutionary phase-search algorithm are employed to calculate the convex hull of the Mo-N binary system. Eight molybdenum nitride compound phases are found to be thermodynamically stable: tetragonal β-Mo3N, hexagonal δ-Mo3N2, cubic γ-Mo11N8, orthorhombic ε-Mo4N3, cubic γ-Mo14N11, monoclinic σ-MoN and σ-Mo2N3, and hexagonal δ-MoN2. The convex hull is a straight line for 0 ≤ x ≤ 0.44 such that bcc Mo and the five listed compound phases with x ≤ 0.44 are predicted to co-exist in thermodynamic equilibrium. Comparing the convex hulls of cubic and hexagonal Mo1-xNx indicates that cubic structures are preferred for molybdenum rich (x &lt; 0.3) compounds, and hexagonal phases are favored for nitrogen rich (x &gt; 0.5) compositions, while similar formation enthalpies for cubic and hexagonal phases at intermediate x = 0.3–0.5 imply that kinetic factors play a crucial role in the phase formation. The volume per atom Vo of the thermodynamically stable Mo1-xNx phases decreases from 13.17 to 9.56 Å3 as x increases from 0.25 to 0.67, with plateaus at Vo = 11.59 Å3 for hexagonal and cubic phases and Vo = 10.95 Å3 for orthorhombic and monoclinic phases. The plateaus are attributed to the changes in the average coordination numbers of molybdenum and nitrogen atoms, which increase from 2 to 6 and decrease from 6 to 4, respectively, indicating an increasing covalent bonding character with increasing x. The change in bonding character and the associated phase change from hexagonal to cubic/orthorhombic to monoclinic cause steep increases in the isotropic elastic modulus E = 387–487 GPa, the shear modulus G = 150–196 GPa, and the hardness H = 14–24 GPa in the relatively narrow composition range x = 0.4–0.5. This also causes a drop in Poisson's ratio from 0.29 to 0.24 and an increase in Pugh's ratio from 0.49 to 0.64, indicating a ductile-to-brittle transition between x = 0.44 and 0.5.