Optimization Transmission Theory and Technical Pathways that Describe Multiscale Urban Agglomeration Spaces

Urban agglomerations are spatial entities that promote the development of ‘new urbanization' processes within China. In this context, the concept of ‘multiscale urban agglomeration spaces' encompasses three linked levels: macroscale urban agglomerations, mesoscale cities, and microscale urban centers. Applying a series of multidisciplinary integrated research methods drawn from geography, urban planning, and architecture, this paper reveals two intensive utilization laws that can be generalized to apply to multiscale urban agglomeration spaces, top-to-bottom ‘positive transmission' linkage and inside-to-outside ‘negative transmission' movement. This paper also proposes optimization transmission theory and policy decision technical pathways that can be applied to these three urban agglomeration spatial scales. Specific technical pathways of transmission include intensive expansion and simulated decision-making in macroscale urban agglomerations, ecology, production, and living space intensive layout and dynamic decision-making in mesoscale cities, and four cores(i.e., ‘single, ring, axis, and pole core') progressive linkage and intensive optimization decision-making in microscale urban centers. The theory and technical pathways proposed in this paper solve the technical problem of optimization and provide intensive methods that can be applied not only at the individual level but also at multiple scales in urban agglomeration spaces. This study also advances a series of comprehensive technical solutions that can be applied to both compact and smart growth cities as well as to urban agglomerations. Solid theoretical support is provided for the optimization of Chinese land development, urbanization, agricultural development, and ecological security.

Transmission upper limit of band-pass double-layer FSS and method of transmission performance improvement

The transmission upper limit of a double-layer frequency selective surface （FSS） with two infinitely thin metal arrays is pre- sented based on the study of the general equivalent transmission line model of a double-layer FSS. Results of theoretical analyses, numerical simulations and experiments show that this transmis- sion upper limit is independent of the array and the element, which indicates that it is impossible to achieve a transmission upper limit higher than this one under a given incident and dielectric- supporting condition by the design of the periodic array. Both the applicable condition and the possible application of the transmis- sion upper limit are discussed. The results show that the transmis- sion upper limit not only has a good reachability, but also provides a key to effectively improve the transmission performance of a double-layer FSS or more complex frequency selective structures.

General Analytic Solution of the Telegrapher’s Equations and the Resulting Consequences for Electrically Short Transmission Lines

Based on classical circuit theory, this article develops a general analytic solution of the telegrapher’s equations, in which the length of the cable is explicitly contained as a freely adjustable parameter. For this reason, the solution is also applicable to electrically short cables. Such a model has become indispensable because a few months ago, it was experimentally shown that voltage fluctuations in ordinary but electrically short copper lines move at signal velocities that are significantly higher than the speed of light in a vacuum. This finding contradicts the statements of the special theory of relativity but not, as is shown here, the fundamental principles of electrical engineering. Based on the general transfer function of a transmission line, the article shows mathematically that an unterminated, electrically short cable has the characteristics of an ideal delay element, meaning that an input signal appears at the output with a slight delay but remains otherwise unchanged. Even for conventional cables, the time constants can be so small that the corresponding signal velocities can significantly exceed the speed of light in a vacuum. The article also analyses the technical means with which this effect can be conveyed to very long cables.

Broad-bandwidth and low-loss metamaterials:theory, design and realization

In this paper, we summarize some recent activities in the field of metamaterial research at the National University of Singapore (NUS). Integral equations are applied for electromagnetic modelling of supernatural materials. Some special charac- teristics of the metamaterials are shown. Moreover, quasi-static Lorentz theory and numerical method (i.e., the method of moments for solving the electric field integral equation) and the transmission line theory are both presented to obtain the effective consti- tutive relations of metamaterials, respectively. Finally, feasibility of fabricating metamaterials based on analysis of equivalent transmission line model in the microwave spectrum and even higher is also shown and correspondingly some broad-bandwidth and low-loss metamaterial structures are designed and synthesized.

The transmission mechanism theory of disease dynamics:Its aims,assumptions and limitations

Most of the progress in the development of single scale mathematical and computational models for the study of infectious disease dynamics which now span over a century is build on a body of knowledge that has been developed to address particular single scale descriptions of infectious disease dynamics based on understanding disease transmission process.Although this single scale understanding of infectious disease dynamics is now founded on a body of knowledge with a long history,dating back to over a century now,that knowledge has not yet been formalized into a scientific theory.In this article,we formalize this accumulated body of knowledge into a scientific theory called the transmission mechanism theory of disease dynamics which states that at every scale of organization of an infectious disease system,disease dynamics is determined by transmission as the main dynamic disease process.Therefore,the transmission mechanism theory of disease dynamics can be seen as formalizing knowledge that has been inherent in the study of infectious disease dynamics using single scale mathematical and computational models for over a century now.The objective of this article is to summarize this existing knowledge about single scale modelling of infectious dynamics by means of a scientific theory called the transmission mechanism theory of disease dynamics and highlight its aims,assumptions and limitations.

Structure and design method for pulse-triggered flip-flops at switch level

A kind of structure and a design method using transmission voltage-switch theory for pulse-triggered flip-flops were proposed,which are suitable for all kinds of pulse-triggered flip-flops and no extra techniques are needed to eliminate the switching activities of internal nodes.Based on the proposed structure and design technique,two pulsed flip-flops were implemented and simulated.The proposed pulsed flip-flops have simple circuit structures.HSPICE simulation shows that the proposed pulsed D flip-flop outperforms the conventional pulsed D flip-flop by 17.2% in delay and 30.1% in power-delay-product(PDP) and the proposed pulsed JK flip-flop has low power and small PDP compared with pulsed D pulsed flip-flops,confirming that the proposed structure and design technique are simple and practical.

Analytical Modeling and Experimental Validation of Electromagnetic Field Radiated by In-house PLC Lines

Broadband PLC （power line communication） technology is a main factor of the development of digital convergence in the indoor network. It uses the already existing power cable infrastructure for communication purposes. The EM （electromagnetic） field radiating from the cable could, however, disturb other communication systems, and thus should be evaluated. The MoM （method of moment） and the FEM （finite element method） have been studied to estimate the EVI field emitted from the power cable. However, the M oM is difficult to treat the dielectric material of the cable and the FEM is time consuming. This paperpresents a new approach to estimate the radiated EM fields caused by PLC sy stems from the CM current along the cable, based on the transmission line theory. The proposed model has the advantage of using the measured primary parameters of the cable. An experimental analysis of the EM radiation distribution is also presented. A comparison showed that the model results agree quite well with the measurements performed in this study.

Analysis and demonstration of PID algorithm based on arranging the transient process for adaptive optics

The fastness and robustness of a control algorithm are highly important in the performance of adaptive optics systems. The proportional-integral-derivative control with arranging the transient process, which is designed using a tracking differentiator, is applied into an adaptive optics system. This control algorithm greatly improves the dynamic properties of the control system. To identify the underlying reasons for these improvements, the influence of the control algorithm is theoretically discussed. The control algorithm is verified by a simple adaptive optics system for tip/tilt correction. The experimental results demonstrate that the control algorithm is fast and robust.

An Improved Modeling of TDR Signal Propagation for Measuring Complex Dielectric Permittivity

Time domain reflectometry（TDR） is a measurement technique based upon transmission line theory. The solutions of transmission line equations are reformulated in terms of independent physical properties, instead of coupled per-unit-length circuit parameters. The complete TDR response is effectively modeled by a non-uniform transmission line using the non-recursive ABCD matrix approach. Approaches to calibrate line parameters and perform TDR measurements based upon such model are introduced with an example on dielectric spectroscopy. TDR modeling in terms of decoupled physical parameters and non-recursive algorithm allows more convenient calibration of line parameters and facilitates interpretation of TDR measurements.