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Electro-optic (EO) modulators are typically made of inorganic materials such as lithium niobate; the replacement of these modulators with organic EO materials is a promising alternative due to their lower half-wave voltage (Vπ), ease of handling, and relatively low cost. We propose the design and fabrication of a push-pull polymer electro-optic modulator with voltage-length parameters (VπL) of 1.28 V·cm. The device uses a Mach–Zehnder structure and is made of a second-order nonlinear optical host-guest polymer composed of a CLD-1 chromophore and PMMA polymer. The experimental results show that the loss is 1.7 dB, Vπ drops to 1.6 V, and the modulation depth is 0.637 dB at 1550 nm. The results of a preliminary study show that the device is capable of efficiently detecting electrocardiogram (ECG) signals with performance on par with that of commercial ECG devices.

In this paper, we are concerned with the validity of Prandtl boundary layer expansion for the solutions to two dimensional (2D) steady viscous incompressible magnetohydrodynamics (MHD) equations in...

We demonstrated the design of two different structures, a two-sided structure and a top-surface structure, of glucose waveguide Bragg grating (WBG) sensors in a single-mode silicon-on-insulator (SOI) chip. A two-sided WBG structure was fabricated, and chip preparation was realized by lithography and other processes. A photonic platform for testing the two-sided WBG using glucose was built and completed. When the blood glucose concentration changed by 1 mg/mL, the two-sided WBG had a wavelength offset of 78 pm. The experimental results show that the two structures can achieve the sensing of different blood glucose concentrations. The two-sided WBG had better sensing performance and thus has a wide range of application prospects.

In this paper, we validate the boundary layer theory for 2D steady viscous incompressible magnetohydrodynamics (MHD) equations in a domain $\{(X, Y)\in[0, L]\times\mathbb{R}_+\}$ under the assumption of a moving boundary at $\{Y=0\}$. The validity of the boundary layer expansion and the convergence rates are established in Sobolev sense. We extend the results for the case with the shear outer ideal MHD flows [3] to the case of the nonshear flows., 61 pages

In this paper, we study the transition threshold problem for the 2-D Navier-Stokes equations around the Poiseuille flow $(1-y^2,0)$ in a finite channel with Navier-slip boundary condition. Based on the resolvent estimates for the linearized operator around the Poiseuille flow, we first establish the enhanced dissipation estimates for the linearized Navier-Stokes equations with a sharp decay rate $e^{-c\sqrt{\nu}t}$. As an application, we prove that if the initial perturbation of vortiticy satisfies $$\|\omega_0\|_{L^2}\leq c_0\nu^{\frac{3}{4}},$$ for some small constant $c_0>0$ independent of the viscosity $\nu$, then the solution dose not transition away from the Poiseuille flow for any time., Comment: 28 pages

In this paper, we establish the mathematical validity of the Prandtl boundary layer theory for a class of nonlinear plane parallel flows of viscous incompressible magnetohydrodynamic (MHD) flow with no-slip boundary condition of velocity and perfectly conducting wall for magnetic fields. The convergence is shown under various Sobolev norms, including the physically important space-time uniform norm $L^\infty(H^1)$. In addition, the similar convergence results are also obtained under the case with uniform magnetic fields. This implies the stabilizing effects of magnetic fields. Besides, the higher-order expansion is also considered., Comment: 28 pages

In this paper, we establish the mathematical validity of the Prandtl boundary layer theory for a class of nonlinear plane parallel flow of nonhomogeneous incompressible Navier-Stokes equations. The convergence for the density and velocity are shown under various Sobolev norms, including the physically important space-time uniform norm, as well as the $L^\infty(H^1)$ norm. It is mentioned that the mathematical validity of the Prandtl boundary layer theory for nonlinear plane parallel flow is generalized to the nonhomogeneous case., 1 figure

This paper concerns with the stability of the plane Couette flow resulted from the motions of boundaries that the top boundary $\Sigma_1$ and the bottom one $\Sigma_0$ move with constant velocities $(a,0)$ and $(b,0)$, respectively. If one imposes Dirichlet boundary condition on the top boundary and Navier boundary condition on the bottom boundary with Navier coefficient $\alpha$, there always exists a plane Couette flow which is exponentially stable for nonnegative $\alpha$ and any positive viscosity $\mu$ and any $a, b \in \mathbb{R}$, or, for $\alpha, Comment: 26 pages; To appear in Comm. Math Sci

Considering bounded torque and the existence of parameter uncertainties, the trajectory tracking control of joint and the active suppression of flexible vibration for a free-floating flexible space robot (FFFSR) are discussed. Based on singular perturbation method, the FFFSR system is decomposed into a slow subsystem tracking joint trajectory and a fast subsystem describing flexible vibration. Then a combination controller including a slow and a fast control component is proposed. For the slow subsystem, an optimized control method is proposed based on State-Dependent Riccati Equation (SDRE), making it possible to optimize the performance index function constituted by the output torque and the tracking error to ensure tracking accuracy while reducing their energy consumption as much as possible. For the fast subsystem, an extended state observer is adopted to estimate the coordinate derivatives of flexible modal and uncertain disturbance that are difficult to measure, and then LQR is used to suppress the flexible vibration. The numerical simulation results show that the combination controller can suppress the flexible vibration effectively while tracking the desired joint trajectory stably with bounded torque.

In this report, we describe the use of universal primer PCR (UPPCR) for the detection of 16S ribosomal RNA (rRNA) genes from Aeromonas hydrophila captured by anti-A. hydrophila antibody coupled to a microplate. The approach combining immuno-capture with UPPCR provides a quick, sensitive, and reproducible way for the detection of bacterial cells.

Based on the principle and characteristics of patternless casting mould's (core's) manufacturing, CAMTC-SMM1000 CNC machine was developed and widely applied in many shapes of moulds' manufacturing. It's revealed that the patternless casting mould manufacturing technology has a promising application prospect in single piece and small batch of metal parts' manufacturing.