Three Novel Nonlinear Wavelength Converters with Built-in Amplitude Modulators

[[abstract]]To achieve simultaneous wavelength conversion and amplitude modulation, we electro-optically modulated a dispersion lithium niobate section in two PPLN sections for a linear-cascaded configuration and a folding-crystal configuration. The performance is compared with an electrode-coated asymmetric-duty-cycle PPLN amplitude modulator.[[fileno]]2030114030026[[department]]電機工程學

Observation of a linear temperature dependence of the critical current density in a Ba_{0.63}K_{0.37}BiO_3 single crystal

For a Ba_{0.63}K_{0.37}BiO_3 single crystal with T_c=31 K, H_{c1}=750 Oe at 5 K, and dimensions 3x3x1 mm^3, the temperature and field dependences of magnetic hysteresis loops have been measured within 5-25 K in magnetic fields up to 6 Tesla. The critical current density is J_c(0)=1.5 x 10^5 A/cm^2 at zero field and 1 x 10^5 A/cm^2 at 1 kOe at 5 K. J_c decreases exponentially with increasing field up to 10 kOe. A linear temperature dependence of J_c is observed below 25 K, which differs from the exponential and the power-law temperature dependences in high-Tc superconductors including the BKBO. The linear temperature dependence can be regarded as an intrinsic effect in superconductors.Comment: RevTex, Physica C Vol. 341-348, 729 (2000

Topological Gauge Theory Of General Weitzenbock Manifolds Of Dislocations In Crystals

General Weitzenbock material manifolds of dislocations in crystals Are proposed, the reference, idealized and deformation states of the bodies in general case are generally described by the general manifolds, the topological gauge field theory of dislocations is given in general case,true distributions and evolution of dislocations in crystals are given by the formulas describing dislocations in terms of the general manifolds,furthermore, their properties are discussed.Comment: 10pages, Revte

Anomalous metamagnetism in the low carrier density Kondo lattice YbRh3Si7

We report complex metamagnetic transitions in single crystals of the new low carrier Kondo antiferromagnet YbRh3Si7. Electrical transport, magnetization, and specific heat measurements reveal antiferromagnetic order at T_N = 7.5 K. Neutron diffraction measurements show that the magnetic ground state of YbRh3Si7 is a collinear antiferromagnet where the moments are aligned in the ab plane. With such an ordered state, no metamagnetic transitions are expected when a magnetic field is applied along the c axis. It is therefore surprising that high field magnetization, torque, and resistivity measurements with H||c reveal two metamagnetic transitions at mu_0H_1 = 6.7 T and mu_0H_2 = 21 T. When the field is tilted away from the c axis, towards the ab plane, both metamagnetic transitions are shifted to higher fields. The first metamagnetic transition leads to an abrupt increase in the electrical resistivity, while the second transition is accompanied by a dramatic reduction in the electrical resistivity. Thus, the magnetic and electronic degrees of freedom in YbRh3Si7 are strongly coupled. We discuss the origin of the anomalous metamagnetism and conclude that it is related to competition between crystal electric field anisotropy and anisotropic exchange interactions.Comment: 23 pages and 4 figures in the main text. 7 pages and 5 figures in the supplementary materia

A Novel Approach to Identify the Thermal Conductivities of a Thin Anisotropic Medium by the Boundary Element Method

A common difficulty arises in characterizing the anisotropic properties of a thin sheet of anisotropic material, especially in the transverse direction. This difficulty is even more phenomenal for measuring its mechanical properties on account of its thickness. As the prelude of such investigation, this paper proposes a novel approach to identify the thermal conductivities of an unknown thin layer of anisotropic material. For this purpose, the unknown layer is sandwiched in isotropic materials with known conductivities. Prescribing proper boundary conditions, one may easily measure temperature data on a few sample boundary points. Therefore, the anisotropic thermal conductivities can be calculated inversely. For the inverse analysis, the boundary element method (BEM) is employed to combine with the conjugate gradient method (CGM). For verifying our analysis, numerical experiments were carried out. The obtained results have shown great computational efficiency and accuracy in identifying the thermal conductivities of the thin anisotropic layer

Mechanical vibration for the control of membrane fouling in direct contact membrane distillation

One of the biggest challenges for direct contact membrane distillation (DCMD) in treating wastewater from flue gas desulfurization (FGD) is the rapid deterioration of membrane performance resulting from precipitate fouling. Chemical pretreatment, such as lime-soda ash softening, has been used to mitigate the issue, however, with significant operating costs. In this study, mechanical vibration of 42.5 Hz was applied to lab-scale DCMD systems to determine its effectiveness of fouling control for simulated FGD water. Liquid entry pressure and mass transfer limit of the fabricated hollow fiber membranes were determined and used as the operational constraints in the fouling experiments so that the observed membrane performance was influenced solely by precipitate fouling. Minimal improvement of water flux was observed when applying vibration after significant (~16%) water-flux decline. Initiating vibration at the onset of the experiments prior to the exposure of foulants, however, was promising for the reduction of membrane fouling. The water-flux decline rate was reduced by about 50% when compared to the rate observed without vibration. Increasing the module packing density from 16% to 50% resulted in a similar rate of water-flux decline, indicating that the fouling propensity was not increased with packing density in the presence of vibration

A switchable pH-differential unitized regenerative fuel cell with high performance

Regenerative fuel cells are a potential candidate for future energy storage, but their applications are limited by the high cost and poor round-trip efficiency. Here we present a switchable pH-differential unitized regenerative fuel cell capable of addressing both the obstacles. Relying on a membraneless laminar flow-based design, pH environments in the cell are optimized independently for different electrode reactions and are switchable together with the cell process to ensure always favorable thermodynamics for each electrode reaction. Benefiting from the thermodynamic advantages of the switchable pH-differential arrangement, the cell allows water electrolysis at a voltage of 0.57 V, and a fuel cell open circuit voltage of 1.89 V, rendering round-trip efficiencies up to 74%. Under room conditions, operating the cell in fuel cell mode yields a power density of 1.3 W cm¯², which is the highest performance to date for laminar flow-based cells and is comparable to state-of-the-art polymer electrolyte membrane fuel cells

Attributions and Outcomes of Customer Misbehavior

The purpose of this study is to determine which attribution dimensions concerning dysfunctional other-customer misbehavior most influence customer dissatisfaction toward a service firm. Our research hypotheses were tested using a 2 (Controllability: controllable versus uncontrollable) x 2 (Stability: unstable versus stable) x 2 (Globality: specific versus global) experimental design in a hypothetical restaurant context. Our empirical results demonstrate that when customers feel that the other-customer's misbehavior can be controlled by the firm (i.e., controllability attributions) or is likely to recur (i.e., stability attributions), they render unfavorable service evaluations toward that firm. However, these harmful effects may be mitigated if the customer believes that the same type of dysfunctional customer behavior also occurs during service encounters in other firms (i.e., globality attributions). With a view to diminishing the unsatisfactory experience of other-customer failure, the service organizations need to: (1) act as "police officers" to ensure that their customers behave appropriately; (2) have policies and procedures in place to manage their guests' behavior so as to reduce the recurrence of other-customer failure; and (3) consider communications intended to enhance attributions of globality following an other-customer failure, that will help to buffer the negative impact of controllability and stability attributions on satisfaction and behavioral reactions with the firm. This is the first time that controllability, stability, and globality attributions are clearly shown to be part of the process by which customers transfer their negative response to other-customer misbehavior to the organization