基于lucidshape的投影型前照灯的曲面设计

Many of today's satellite communication and radar systems necessitate phased array antennas that are capable of wideband/multi-band operation and good polarization purity over a wide scan volume. However, the antenna solutions typically used for wideband wide-scan applications trade-off matching performance against polarization purity. For this reason, in recent years, a new approach has arisen for the design of broadband arrays, aiming at reducing cross polarization. This antenna solution consists of arrays of long dipoles or slots periodically fed, and are referred to as connected arrays of slot or dipoles. Connected array antennas represent one of the most promising concepts in the field of very wideband arrays, for being able to achieve both broad band and low cross polarization. The wideband performance is due to the fact that the connections between neighboring elements allow currents to remain nearly constant with frequency. Another attractive feature of connected arrays is their capability to achieve good polarization purity, in virtue of the planarity of the radiators. Besides the advantageous physical properties, connected arrays are based on simple geometries that lead to the derivation of analytical solutions for the antenna parameters. Closed-form expressions based on a spectral Green's function representation are derived for the input impedance, the current distribution over the array and the radiation patterns. Important advantages result from this representation with respect to numerical solutions: above all, the reduction of computational costs and the gain in physical insight on the wave phenomena. A convenient circuit representation of the array unit cell is derived. The circuit describes rigorously and analytically the transition between free-space radiation and guiding transmission line. Contrarily to standard Thevenin circuit for receiving antennas, this representation can be used to evaluate the power scattered by the antenna. The results have been applied to the analysis of the scattering and absorption of a real connected-dipole prototype array backed by a frequency selective ground plane. Good agreement was achieved between measurements and results from the equivalent network. A novel measurement technique based on passive RCS measurements in the main planes was used to characterize the active matching of the radiating part of the antenna in transmission. Finiteness effects can be particularly severe in connected arrays, due to electrical connection and the high mutual coupling between the elements. As a consequence, the overall behavior of a finite wideband array can be sensibly different with respect to infinite array analysis. Thus, it is crucial to include edge effects already in the preliminary assessment of the array performance. An efficient numerical procedure is derived for the characterization of the edge effects. The method requires only one unknown per elementary cell, independently from the cell geometrical parameters. This is possible thanks to the use of an appropriate connected array Green's function in the integral equation. This procedure is of general applicability and can be used for arrays with and without backing reflectors and for arbitrary scan angle. An alternative analytical representation is also derived to provide physical insight on the nature of the edge-waves. The analytical approximation of the spatial current distribution on the finite array is derived, for the specific case of a connected array of dipoles operating in free space, and scanning only in the E-plane. The key step is to represent the total current as sum of the infinite array contribution plus edge-born waves. The final analytical expression is given in terms of Fresnel functions and allows qualitative considerations on the nature of the electric current distribution, in terms of spreading and attenuation. The analytical expressions represent a powerful tool that can be used both for modeling and design. A connected array of dipoles with 40% bandwidth, when scanning in elevation to 45o, has been designed. Practical designs require the implementation of ad hoc feed structures that avoid common-mode currents to propagate on the feed lines. This problem has been addressed and feed structures that perform common-mode rejection have been designed. Measurements form a prototype demonstrator were presented for validation and showed good performance.

Institutional transition is a critical phase that requires students’ ability to adapt the changes and continue their routine without stress. Accordingly, a quantitative study which involved 95 students was conducted in Malaysia Institute of Teacher Education. The main objective of the study is to develop institutional transition model (TIPP) based on students’ adjustment. Schlossberg's transition theory became the basis of the TIPP model and Student Adaptation to College Questionnaire (SACQ) is used as an instrument to measure students’ transition. The study population is students from Preparatory Programme Bachelor of Teaching (PPISMP) majoring in Mathematics Education. This study aims to examine the relationship between four components of adjustment (academic, social, personal-emotional and institutional commitment). Research model is developed and tested using a Structural Equation Model-Partial Least Squares (SEM-PLS) analysis. The findings of the study showed that five out of six hypotheses on the structural model were significant. Academic adjustment has the most significant relationship with the personal emotion adjustment. While social adjustment has the most significant relationship with the institution’s commitment. The study successfully proposed TIPP structural model based on Schlossberg's transition theory and able to show the relationship between four components of adjustment.

Low temperature detectors have been a subject of intense interest to the scientific community over the last decade. These detectors work at very low temperatures, often well below 1 Kelvin, to minimize the noise in the measurement of photons. This leads to very powerful detectors applicable to a broad wavelength range. Since these detectors are so sensitive even single pixels and small arrays (up to several hundred pixels) enable deeper explorations of the cosmos than ever before. Instruments based on these technologies have been used at submillimeter, optical, and X-ray wavelengths. The scientific prospects for these detectors increase as they grow in pixel count. For some applications, especially for Cosmic Microwave Background (CMB) polarization work, a large focal plane will not only increase efficiency but will also enable new and vital science. Current superconducting technologies, such as Transition Edge Sensors (TESs), can currently deliver extremely high sensitivity in the submillimeter and read-noise free imaging spectroscopy at Optical/UV and X-ray wavelengths, but the largest arrays contain less that 100 pixels. In order to make real progress these arrays must contain many thousands of pixels. This is a formidable technical challenge. This thesis will explore a promising emerging technology called Microwave Kinetic Inductance Detectors (MKIDs). MKIDs make use of the change in the surface impedance of a superconductor as incoming photons break up Cooper pairs. This is accomplished by making the strip of superconductor part of a microwave resonant circuit, and monitoring the phase of a signal transmitted through (or past) the resonator. The primary advantage of this technology is that by using resonant circuits with high quality factors, passive frequency domain multiplexing will allow up to thousands of resonators to be read out through a single coaxial cable and a single HEMT amplifier. This eliminates the cryogenic electronics (SQUIDS) and wiring problems associated with current superconducting devices. Inexpensive and powerful room-temperature readout electronics can leverage the microwave integrated circuits developed for wireless communications. When this project started four years ago MKIDs were just a concept. In this thesis I will recount the progress we have made in taking this concept and turning it into a detector technology, building on the work we published in Nature in 2003. I will demonstrate that we have overcome the major technical obstacles and shown conclusively that MKIDs work, and should provide much larger arrays than are possible with other technologies. Due to our work at Caltech and JPL, MKIDs are considered one of the leading technologies to reach the ambitious goals set for future ground and space missions. The noise performance is already good enough for sky-limited, ground-based, submillimeter astronomy. Despite MKIDs acceptable noise performance for ground-based astronomy, there are many applications which require lower detector noise. The simple MKIDs we measure in this thesis still exhibit a noise higher than theory would predict which could limit their usefulness for some applications. In Chapters 7-9 we perform several experiments which identify the source of the excess noise as the substrate. In the course of these experiments to characterize and identify the noise, we successfully demonstrate two distinct approaches which dramatically reduce the noise excess.

Water splitting for hydrogen production under sunlight using TiO2 as photo catalyst provides a better route for solar energy and attracts the attention of many researchers. The photo catalytic activity of TiO2 under sunlight irradiation depends on the band gap energy. The transition metal doped TiO2 shows an edge over TiO2 in optical absorbance and photo catalytic activity. Thin film of Cr doped TiO2was deposited by Electron beam evaporation deposition process on glass substrate, the band gap of sample was measured with UV-Vis spectroscopy. In order to provide theoretical ground to our experimental band gap results the first principle (ab-initio) calculation was performed using the computer code WIEN2K with Full Potential Linearized Augmented Plane Wave method (FP-LAPW) based on the density functional theory (DFT).

This study aims to show how to obtain the curvature of the ellipsoid depending on azimuth angle. The curvature topic is quite popular at an interdisciplinary level. It can be to the friends of geometry, geodesy, satellite orbits in space, in studying all sorts of elliptical motions (e.g., planetary motions), curvature of surfaces and concerning eye-related radio-therapy treatment, for example the anterior surface of the cornea is often represented as ellipsoidal in form. On the calculation of the curvature, there is a famous Euler formula for rotating ellipsoid that everyone knows. Let θ be the angle, in the tangent plane, measured clockwise from the direction of minimum curvature κ1. Then the normal curvature κn (θ) in direction θ is given by κn (θ) = κ1 cos2θ + κ2 sin2θ = κ1 + (κ2 - κ1) cos2θ I wonder how can a formula for a triaxial ellipsoid? So we started to work. And we finally found the formula for the triaxial ellipsoid.

The present work deals with the effect of an external circumferential elliptical crack located at thickness transition on a varied stepped diameter pipe . The purpose is the application of the extended finite element method (XFEM) for the calculation of SIF at the thickness transition region of pipe considering internal pressure and compare the effect of the crack between pipes straight and with thickness transition. To model a crack with precision , enrichment functions are used to enrich the displacement approximation, the level set functions are calculated from the crack mesh and definition of the strategy of integration has been performed. A comparative study is made on SIF of crack defect in straight pipe compared to one with thickness transition using XFEM for the crack and pipe geometrical parameters variations. The result shows that the XFEM is an effective and practical tool for elliptic crack modeling in a pipe with thickness transition because a crack is easily modeled through enrichment functions.The comparison of the SIF of a similar defect between pipes shows that a pressurized pipe with thickness transition is more sensitive to the used cracks.

Safety, security, and comfort of pedestrians are important to be accommodated by a pedestrian path, especially at night. This study aimed at measuring the quality of artificial lighting in the pedestrian path at Malioboro Street in Yogyakarta, Indonesia. This study employed a qualitative method by measuring visual perception of the pedestrian paths through semantic differential scale method. Results of visual perception of the quality of nighttime lighting were then analyzed by comparing the quantity of light at nighttime measured using a light meter. The quantity and quality of daylight were also measured as a comparison in the analysis process. From field observations, measurements and analysis, it was found that the quality of artificial lighting in the pedestrian path at Malioboro Street, did not meet the visual needs of pedestrians. In contrast, at daytime, the visual perception of the pedestrians indicated good results, but the lack of lighting led to different results at nighttime. It can be concluded that the quality of the lighting in pedestrian paths at Malioboro Street, should be improved through lighting design, which is able to meet the visual needs of the users. Good pedestrian path lighting will promote comfort, safety, and security of the users.

(2001). Solution of a Calculus Problem on Minimal Volume. The American Mathematical Monthly: Vol. 108, No. 3, pp. 217-221.

Based on the recent work of R. Lindberg on transverse collective instabilities it was observed that if the ratio of quadrupolar to dipolar impedance ρ is equal to -1 there is no TMC-instability. This relationship is actually fulfilled by resistive wall (RW)-impedance on the horizontal plane in case of a flat vacuum chamber. HEADTAIL simulations were carried out to check if this observation can be confirmed. Additionally the effect of radial modes on the TMC-instability was studied.

The objective of this article is investigation of dynamic response of thick multilayer functionally graded (FG) beam under generalized dynamic forces. The plane stress problem is exploited to describe the constitutive equation of thick FG beam to get realistic and accurate response. Applied dynamic forces are assumed to be sinusoidal harmonic, sinusoidal pulse or triangle in time domain and point load. Equations of motion of deep FG beam are derived based on the Hamilton principle from kinematic relations and constitutive equations of plane stress problem. The numerical finite element procedure is adopted to discretize the space domain of structure and transform partial differential equations of motion to ordinary differential equations in time domain. Numerical time integration method is used to solve the system of equations in time domain and find the time responses. Numerical parametric studies are performed to illustrate effects of force type, graduation parameter, geometrical and stacking sequence of layers on the time response of deep multilayer FG beams.

Magnetized, cold, dense molecular cloud cores provide the birth environment for stars, discs, and planets. The multi-scale scenario of low-mass star formation occurs via the formation of two quasi-hydrostatic cores. Furthermore, the conservation of angular momentum can lead to the formation of a disc around the second core (i.e.~the forming protostar). During these early stages of star formation, magnetically driven outflows and jets can be launched from the first and second cores, respectively. Star, disc, and outflow formation involve complex physical processes, which require a robust, self-consistent numerical treatment. In this thesis, we use numerical simulations to probe the gravitational collapse scenario that involves the transition of an isolated molecular cloud core to a hydrostatic core with a surrounding disc. We use the \emph{PLUTO} code to perform radiation (magneto-)hydrodynamic (MHD) collapse simulations, using one- and two-dimensional (2D) grids. We include the effects of self-gravity and a grey flux-limited diffusion approximation for the radiative transfer. Additionally, we use for the gas equation of state density- and temperature-dependent thermodynamic quantities to account for the dissociation, ionisation, and molecular vibrations and rotations. Our spherically symmetric simulations span seven orders of magnitude in spatial scale. We survey a wide range of initial low- to high-mass (0.5 -- 100~$M_{\odot}$) molecular cloud cores, yielding the largest parameter scan so far. Our results highlight the dependence of the first and second hydrostatic core properties on the initial cloud core properties. These simulations indicate that in the high-mass regime, the first hydrostatic cores do not have enough time to form due to large accretion rates. We further expand our studies to three different sets of 2D simulations using axial and midplane symmetry. First, we perform 2D simulations for non-rotating molecular cloud cores with masses of 1~$M_{\odot}$, 5~$M_{\odot}$, 10~$M_{\odot}$, and 20~$M_{\odot}$. For each of these cases, we use an unprecedented resolution to model the evolution of the second core for $\geq$~100 years after its formation. For the first time, we demonstrate that convection is generated in the outer layers of the second core. This supports the intriguing possibility that dynamo-driven magnetic fields may be generated during the earliest phases of star formation. Following which, for the 1~$M_{\odot}$ case, we analyse the effects of solid-body rotation on the properties of the hydrostatic cores and disc formation. In this model, the first hydrostatic core evolves into a more oblate, pseudo-disc like structure and a sub-au disc starts forming after the formation of the second core. Finally, we explore the effects of ideal and non-ideal (including Ohmic resistivity) MHD during the collapse of rotating molecular cloud cores. We investigate the dependence of molecular outflows and disc formation on the initial cloud core mass, rotation, resistivity, and magnetic field strength. We find the presence of magnetically driven outflows launched from both first and second cores in the resistive models. We also reveal ongoing disc formation in some of our resistive simulations. In conclusion, we use detailed thermodynamical modelling to quantify the properties of the hydrostatic cores, outflows, and discs for collapse scenarios with a wide range of initial cloud core properties. The models presented herein will serve as the foundation for follow-up studies that link these theoretical insights with observational signatures.

The area of parameterized approximation seeks to combine approximation and parameterized algorithms to obtain, e.g., (1+epsilon)-approximations in f(k,epsilon)n^O(1) time where k is some parameter of the input. The goal is to overcome lower bounds from either of the areas. We obtain the following results on parameterized approximability: - In the maximum independent set of rectangles problem (MISR) we are given a collection of n axis parallel rectangles in the plane. Our goal is to select a maximum-cardinality subset of pairwise non-overlapping rectangles. This problem is NP-hard and also W[1]-hard [Marx, ESA'05]. The best-known polynomial-time approximation factor is O(log log n) [Chalermsook and Chuzhoy, SODA'09] and it admits a QPTAS [Adamaszek and Wiese, FOCS'13; Chuzhoy and Ene, FOCS'16]. Here we present a parameterized approximation scheme (PAS) for MISR, i.e. an algorithm that, for any given constant epsilon>0 and integer k>0, in time f(k,epsilon)n^g(epsilon), either outputs a solution of size at least k/(1+epsilon), or declares that the optimum solution has size less than k. - In the (2-dimensional) geometric knapsack problem (2DK) we are given an axis-aligned square knapsack and a collection of axis-aligned rectangles in the plane (items). Our goal is to translate a maximum cardinality subset of items into the knapsack so that the selected items do not overlap. In the version of 2DK with rotations (2DKR), we are allowed to rotate items by 90 degrees. Both variants are NP-hard, and the best-known polynomial-time approximation factor is 2+epsilon [Jansen and Zhang, SODA'04]. These problems admit a QPTAS for polynomially bounded item sizes [Adamaszek and Wiese, SODA'15]. We show that both variants are W[1]-hard. Furthermore, we present a PAS for 2DKR. For all considered problems, getting time f(k,epsilon)n^O(1), rather than f(k,epsilon)n^g(epsilon), would give FPT time f'(k)n^O(1) exact algorithms by setting epsilon=1/(k+1), contradicting W[1]-hardness. Instead, for each fixed epsilon>0, our PASs give (1+epsilon)-approximate solutions in FPT time. For both MISR and 2DKR our techniques also give rise to preprocessing algorithms that take n^g(epsilon) time and return a subset of at most k^g(epsilon) rectangles/items that contains a solution of size at least k/(1+epsilon) if a solution of size k exists. This is a special case of the recently introduced notion of a polynomial-size approximate kernelization scheme [Lokshtanov et al., STOC'17].

According to the principle of dielectrophoresis, an aspherical double-liquid lens based on parallel plate electrodes is designed. In comparison with the liquid lenses based on patterned-electrodes, the aspherical double-liquid lens structure uses continuous electrodes, which have the advantages of simpler processing, lower cost, easier realization and more practicability. The droplet in the dielectric electrophoretic liquid lens is polarized in the electric field and moves towards the higher electric field intensity under the action of the dielectrophoretic force. With the change of applied voltage, the dielectrophoretic force varies, thus the contact angle of the droplet at the liquid-liquid interface is changed. Firstly, the models of aspherical double-liquid lenses under different voltages are established with Comsol software, and the data of interfacial profile are derived. Then using Matlab software, the derived interface surface data are fitted by polynomial, and the aspherical coefficients are obtained. Finally, the optical models are built with Zemax software, and the variation range of focal length and root mean square (RMS) radius of aspherical double-liquid lens under different voltages are analyzed. In order to further study the characteristics of aspherical double-liquid lens, it is compared with spherical double-liquid lens model. The liquid material, cavity structure and droplet volume of spherical double-liquid lens are consistent with those of aspherical double-liquid lens. The corresponding spherical double-liquid lens model is established by using the Zemax software, the range of focal length and RMS radius of spherical double-liquid lens under different voltages are obtained. The results show that the focal length variation range of aspherical double-liquid lens is larger than that of spherical double-liquid lens, and the imaging quality of the former is better than that of the latter. The experimental preparation of the designed aspherical double-liquid lens device is carried out, and its focal length and imaging resolution are measured. When the operating voltage is in a range of 0–280 V, the focal length varies from 54.2391 to 34.5855 mm, which is basically consistent with the simulation result. The feasibility of the liquid lens structure is verified experimentally. The imaging resolution can reach 45.255 lp/mm. The designed aspherical double-liquid lens based on the parallel plate electrode can provide a new scheme for the high-quality imaging of liquid lens and its application, and can expand the application scope of liquid lens.

Transverse beam instabilities had been observed in the LHC when the tunes were moving closer together (Laslett tune shift at injection) or when the coupling was known to be large (the beam measurement of the closest tune approach, |C-| showed an increase to approximately the tune separation). This knowledge, in addition to the examples of transverse beam instabilities seen during the energy ramp at the HERA proton ring, hinted at a link between linear coupling and transverse stability. Linear coupling had been used in the Proton Synchrotron (PS) at CERN to stabilise a strong horizontal instability by coupling into the vertical plane. This was possible due to a sharing of the instability rise times between the two planes. These two sets of observations are seemingly in contradiction to each other. This provided the motivation for a study into how linear coupling plays a role in transverse beam stability in the LHC.

Exciton-polarons in self-assembling helical aggregates: relating optical properties to supramolecular structure