General Design Rules Research Articles

General Design Rules for the Synthesis of Dispersion and Dispersion Slope Compensation FIR and IIR Filters With Reduced Complexity

Chromatic dispersion is one of the main transmission impairments in optical systems with high bit rates, because the dispersion limit scales with the square of the data rate. Optical delay-line filters can be used to compensate dispersion and dispersion slope. They can be designed as feedforward finite-impulse response filters or as all-pass infinite-impulse response filters. Due to the time-variant property of the dispersion, those filters have to be adaptive, which requires fast and reliable calculation of the filter coefficients. In this paper, a new approach to calculate filter coefficients by applying analytical methods is presented. Design examples are given, and the filter performance is discussed.

SOME DESIGN RULES FOR CHAOS-BASED ENCRYPTION SYSTEMS

During the past decade a large number of chaos-based encryption systems have been suggested and investigated. Cryptographical analysis of these systems shows that some of them are cryptographically weak. In this paper, some general design rules for chaos-based encryption systems are derived based on strengths and weaknesses of already suggested systems.

OPTIMAL HEPATITIS B VIRUS PRIMER SEQUENCE DESIGN FOR ISOTHERMAL AMPLIFICATION

We have reported the successful use of the Loop Mediated Isothermal Amplification (LAMP) reaction for Hepatitis B Virus (HBV) DNA in a 25 μl micro-reactor for the development of a rapid diagnostic device recently. This method shows the successful amplification of HBV DNA with high specificity and sensitivity efficiently within one hour. Such a powerful method can be used for many other fast diagnostic applications with the help of optimal primer design and miniaturization of reactor. In this report, we will first summarize the general design rules for primer design from literature reviews and our experimental results. We will discuss the effects of HBV primers and concentrations of working buffers for optimal performance.

Design of WDM Cross Connect Based on Interleaved AWG (IAWG) and a Phase Shifter Array

A general design rule for interleaved arrayed waveguide gratings (IAWGs) is derived. A 1timesN WDM switch that is based on a phase shifter array, which is sandwiched between two N-IAWGs, is systematically analyzed. A practical design example of a 1times4 nonblocking wavelength division multiplexing (WDM) switch is detailed to illustrate the design steps and the required phase assignment of each phase shifter for various output states. Based on the reciprocity principle, a simplified structure of the 1timesN WDM switch is proposed, which requires only one N-IAWG with total reflection implemented at the end of each phase shifter. This type of NtimesN WDM switch can be used as a fundamental building block to construct the nonblocking WDM all-optical switch that will be indispensable for future all-optical networks.

Fatigue Life Estimation for Welds of Truck Frames for Rolling Stock Using Stress Frequency in Service Load

The fatigue strength of weld surface of truck frames has been estimated according to the fatigue limit diagram in JIS E 4207, “General Rules for Design of Truck Frames for Railway Rolling Stock”. However, it is impossible to predict the fatigue life by using this fatigue limit diagram. This study has proved the possibility of fatigue life estimation for welds of truck frames according to the Modified Miner's rule. In order to estimate the fatigue life, three items are used such as the S-N diagram assumed from allowable stress in JIS E 4207 or fatigue design curve of JSSC, relation of crack occurrence vs. running distance and stress frequency distribution in service load.

Single mode, polarization-independent submicron silicon waveguides based on geometrical adjustments

In this work, we demonstrate via computer simulation the single mode and zero birefringence conditions for photonic wires with height and width less than 600 nm. We report on the simulation conditions for both single mode and zero birefringence in silicon-on-insulator photonic wires and sub-micron rib waveguides using a 3-dimensional imaginary beam propagation method. The results show that operation in both single mode and zero birefringence is possible under certain circumstances and that the conditions are restricted by fabrication processes where birefringence is strongly dependent upon waveguide dimensions. A matrix of waveguide parameters has been identified at both operating wavelengths of 1310 nm and 1550 nm, which can satisfy single mode and zero birefringence conditions simultaneously. This is to provide a general design rule for waveguides in small dimensions on the order of hundreds of nanometres.

Portable proton exchange membrane fuel-cell systems for outdoor applications

A hydrogen fuelled, 30 W proton exchange membrane fuel-cell (PEMFC) system is presented that is able to operate at an ambient temperature between −20 and 40 °C. The system, which comprises the fuel-cell stack, pumps, humidifier, valves and blowers is fully characterized in a climatic chamber under various ambient temperatures. Successful cold start-up and stable operation at −20 °C are reported as well as the system behaviour during long-term at 40 °C. A simple thermal model of the stack is developed and validated, and accounts for heat losses by radiation and convection. Condensation of steam is addressed as well as reaction gas depletion. The stack is regarded as a uniform heat source. The electrochemical reaction is not resolved. General design rules for the cold start-up of a portable fuel-cell stack are deduced by the thermal model and are taken into consideration for the design. The model is used for a comparison between active-assisted cold start-up procedures with a passive cold start-up from temperatures below 0 °C. It is found that a passive cold start-up may not be the most efficient strategy. Additionally, the influence of different stack concepts on the start-up behaviour is analysed by the thermal model. Three power classes of PEMFC stacks are compared: a Ballard Mk902 module for automotive applications with 85 kW, the forerunner stack Ballard Mk5 (5 kW) for medium power applications, and the developed OutdoorFC stack (30 W), for portable applications.

Geometry optimization for planar piezoresistive stress sensors based on the pseudo-Hall effect

The dependence of the sensitivity of planar piezoresistive stress sensors on geometry is systematically analyzed. The sensors in this paper are based on the shear piezoresistance effect, also termed pseudo-Hall effect. The analyzed geometry parameters are: (i) the shape of the device active area, (ii) its aspect ratio and (iii) the location and size of input and output contacts. Further, the influence of non-conducting islands in the active device area was investigated. General design rules for the design of piezoresistive stress sensors with improved sensitivity were extracted. These results were obtained using a simulation approach combining affine mapping with the finite element method. The simulation program was tested by comparing simulation results with experimental data obtained from stress sensors fabricated in CMOS technology. The differences between simulated and measured results were between 1.2 and 3.3%. Novel optimized sensor geometries with non-conducting islands show simulated and measured sensitivities greatly improved by factors up to 2.30 and 2.39, respectively. Further, the new sensors with non-conducting islands are put in perspective with classical Wheatstone bridges.

Efficiency of mineral admixtures in mortars: Quantification of the physical and chemical effects of fine admixtures in relation with compressive strength

This work is the fourth part of an overall project the aim of which was the development of general mix design rules for concrete containing different kinds of mineral admixtures. The two first parts presented the separation and quantification, by means of an empirical model based on semi-adiabatic calorimetry measurements, of the different physical effects responsible for changes in cement hydration (short terms) when chemically inert quartz powders were used in mortars. Part three dealt with an intensive experimental program, presenting and commenting more than 2000 compressive strength measurements. This program concerned 1 day to 6 months old mortars containing up to 75% of inert and pozzolanic admixtures. All these compressive strength results are analyzed in this fourth part and the influence of three effects, namely dilution, heterogeneous nucleation and the pozzolanic effect, are discriminated and quantitatively evaluated. An efficiency concept is proposed in order to take into account the effect of mineral admixture in mortars from both the physical and chemical points of view. It uses an efficiency function ξ( p) that has notable properties: it is independent of time, independent of fineness and independent of the type of mineral admixture.

Shading simulation of the courtyard form in different climatic regions

This paper presents a modelling study carried out into the effect of rectangular courtyard proportions on the shading and exposure conditions produced on the internal envelope of the form in four different locations. These locations, Kuala Lumpur, Cairo, Rome and Stockholm, were chosen to represent the climatic regions of hot humid, hot dry, temperate and cold climates, respectively. The study highlights the effect of the climatic conditions on the suggested courtyard ratios and heights to achieve a reasonable annual performance in the examined locations. Also, it clarifies the variation in the courtyard daily shading and exposure performances as a result of changing the location latitude and consequently the sun's position in the sky. The study suggests guidelines and general rules for efficient courtyard design in the considered climatic regions. Furthermore, it states the ranges within which the parameters of the form can be changed with minimum deviation from the optimum performance. The results showed that the shading conditions of the courtyard internal envelope are significantly dependent on the form's proportions, location latitude and available climatic conditions.

RF current distribution and topology of RF sheath potentials in front of ICRF antennae

The 2D (radial/poloidal) spatial topology of RF-induced convective cells developing radially in front of ion cyclotron range of frequency (ICRF) antennae is investigated, in relation to the spatial distribution of RF currents over the metallic structure of the antenna. This is done via a Green's function, determined from the ICRF wave coupling equations, and well-suited to open field lines extending toroidally far away on both sides of the antenna. Using such formalism, combined with a full-wave calculation using the 3D antenna code ICANT (Pécoul S. et al 2000 Comput. Phys. Commun. 146 166–87), two classes of convective cells are analysed. The first one appears in front of phased arrays of straps, and depending on the strap phasing, its topology is interpreted using the poloidal profiles of either the RF current or the RF voltage of the strip line theory. The other class of convective cells is specific to antenna box corners and is evidenced for the first time. Based on such analysis, general design rules are worked out in order to reduce the RF-sheath potentials, which generalize those proposed in the earlier literature, and concrete antenna design options are tested numerically. The merits of aligning all strap centres on the same (tilted) flux tube, and of reducing the antenna box toroidal conductivity in its lower and upper parts, are discussed.

Structure−Function Studies on a Synthetic Guanosine Receptor That Simultaneously Binds Watson−Crick and Hoogsteen Sites

[structure: see text] A series of receptors (11-16) designed to simultaneously bind the Watson-Crick and Hoogsteen sites of guanosine were synthesized, and their binding of guanosine tri-O-pentanoate (32) was probed via 1H NMR complexation studies in 5% DMSO-d6-chloroform-d. The guanosine receptors were synthesized with aminonaphthalene or aminoquinoline auxiliary groups tethered to N-4 of cytosine via a methylene or carbonyl group. A structure-function relationship was established allowing energetic contributions made by components of nucleoside analogues to be probed and more general design rules formulated that may guide the development of more efficacious DNA bases.

Mineral admixtures in mortars

This work is the second part of an overall project, the aim of which is the development of general mix design rules for concrete containing different kinds of mineral admixtures. The first part presented the separation of the different physical effects responsible for changes in cement hydration when chemically inert quartz powders are used in mortars. This second part describes the development of an empirical model, based on semiadiabatic calorimetry measurements, which leads to the quantification of the enhancement of cement hydration due to the heterogeneous nucleation effect at short hydration times. Experimental results show that not all the admixture particles participate in the heterogeneous nucleation process. Consequently, the concept of efficient surface Seff is introduced in the model. Seff is the total admixture surface S (m2 of mineral admixture/kg of cement) weighted by a function ξ(p). The efficiency function ξ(p) depends only on the replacement rate p and is independent of time, fineness and type of mineral admixture used. It decreases from 1 to 0: Low replacement rates give an efficiency value near 1, which means that all admixture particles enhance the hydration process. An efficiency value near 0 is obtained for high replacement rates, which indicates that, from the hydration point of view, an excess of inert powder does not lead to an increase in the amount of hydrates compared with the reference mortar without mineral admixture. The empirical model, which is mainly related to the specific surface area of the admixtures, quantifies the variation of the degree of hydration induced by the use of inert mineral admixtures. One application of the model, coupled with Powers' law, is the prediction of the short-term compressive strength of mortars.

Optimal design of compact recuperators for microturbine application

This paper presents a new approach for the optimization of microturbine recuperators from the technical and economic standpoints. The procedure proposed has been implemented in the software called CHEOPE (compact heat exchanger optimization and performance evaluation), which considers two types of recuperator concept, which have proved to be the most promising for microturbine applications: the furnace-brazed plate-fin type and the welded primary surface type. The general design rules for performance evaluation of gas–gas heat exchangers are summarized and specifically applied to these two types of recuperator. Moreover, the cost equation, employed to estimate the capital cost of these types of heat exchanger, is discussed. With regard to the sizing procedure, a special optimization procedure of the recuperator matrix has been developed, which takes into account several targets in a single multi-objective function: the compactness, the pressure drops and the expected cost of the device. The tests performed for the validation are presented, and three case studies are illustrated for three different microturbine sizes, for a 50 kW, 100 kW and 500 kW machine, respectively.

Micromechanical tunable optical filters: general design rules for wavelengths from near-IR up to 10 μm

General design rules and the scaling laws with wavelength for MEMS tunable optical filters are discussed for the first time. We describe how to determine dimensions and component materials from the system requirements such as tuning range, central wavelength, tuning voltage, tuning speed and resolution. The systematic design allows fair comparison among different topologies such as cantilever, bridge and trampoline. Design examples are shown for filters with center wavelengths at 850 nm and 4 μm.

Mineral admixtures in mortars effect of type, amount and fineness of fine constituents on compressive strength

This work is the third part of an overall project the aim of which is the development of general mix design rules for concrete containing different kinds of mineral admixtures (also named mineral additions or mineral constituents). It deals with the compressive strength of mortars made with up to 75% of crushed quartz, limestone filler or fly ash of different fineness. The paper presents all the experimental results as a sort of database and emphasizes the effects on strength of the nature, amount and fineness of mineral admixtures. For short hydration times (1 to 2 days), the nature of mineral admixture is not a significant parameter, as mortars containing the same amount of different kinds of admixtures having equivalent fineness present similar strengths. For long hydration times (up to 6 months), the excess strength due to fly ash pozzolanic activity is quantified by the difference between the strengths of mortars containing the same proportions of inert and pozzolanic admixtures with the same fineness. In the case of inert mineral admixtures, the increase in strength with the fineness of mineral admixtures cannot be explained by the filler effect, but can be attributed to the physical effect of heterogeneous nucleation. In the next part of this work, these results will be used for the elaboration of an empirical model leading to the quantification of both physical and chemical effects. This model presents strong similarities with the previous model based on calorimetric results.

Improving precipitation measurement

AbstractAlthough rainfall has been measured for centuries scientifically and in isolated brief episodes over millennia for agriculture, it is still not measured adequately even today for climatology, water resources, and other precise applications. This paper outlines the history of raingauges, their errors, and describes the field testing over 3 years of a ‘first guess’ design for an aerodynamic rain collector proposed by Folland in 1988. Although shown to have aerodynamic advantage over a standard 5″ gauge, the new rain collector was found to suffer from outsplash in heavy rain. To study this problem, and to derive general basic design rules for aerodynamic gauges, its performance was investigated in turbulent, real‐world conditions rather than in the controlled and simplified environment of a wind tunnel or mathematical model as in the past. To do this, video records were made using thread tracers to indicate the path of the wind, giving new insight into the complex flow of natural wind around and within raingauges. A new design resulted, and 2 years of field testing have shown that the new gauge has good aerodynamic and evaporative characteristics and minimal outsplash, offering the potential for improved precipitation measurement. Copyright © 2004 Royal Meteorological Society

Mineral admixtures in mortarsQuantification of the physical effects of inert materials on short-term hydration

Abstract This work is the second part of an overall project, the aim of which is the development of general mix design rules for concrete containing different kinds of mineral admixtures. The first part presented the separation of the different physical effects responsible for changes in cement hydration when chemically inert quartz powders are used in mortars. This second part describes the development of an empirical model, based on semiadiabatic calorimetry measurements, which leads to the quantification of the enhancement of cement hydration due to the heterogeneous nucleation effect at short hydration times. Experimental results show that not all the admixture particles participate in the heterogeneous nucleation process. Consequently, the concept of efficient surface Seff is introduced in the model. Seff is the total admixture surface S (m2 of mineral admixture/kg of cement) weighted by a function ξ(p). The efficiency function ξ(p) depends only on the replacement rate p and is independent of time, fineness and type of mineral admixture used. It decreases from 1 to 0: Low replacement rates give an efficiency value near 1, which means that all admixture particles enhance the hydration process. An efficiency value near 0 is obtained for high replacement rates, which indicates that, from the hydration point of view, an excess of inert powder does not lead to an increase in the amount of hydrates compared with the reference mortar without mineral admixture. The empirical model, which is mainly related to the specific surface area of the admixtures, quantifies the variation of the degree of hydration induced by the use of inert mineral admixtures. One application of the model, coupled with Powers' law, is the prediction of the short-term compressive strength of mortars.

Carrier-confined vertical-cavity semiconductor optical amplifiers for higher gain and efficiency

Vertical-cavity semiconductor optical amplifiers (VCSOAs) are interesting devices because of their small form factor, potential low manufacturing cost, high coupling efficiency to optical fiber, and polarization-independent gain. We present an overview of the properties of VCSOAs, as well as emerging applications for this new class of devices. We present general design rules and analyze how the mirror reflectivity affects the properties of the VCSOA. Experimental results of carrier-confined, optically pumped VCSOAs operating at 1.3-μm wavelength are presented. The devices were fabricated by wafer bonding high-quality AlGaAs distributed Bragg reflectors (DBRs) to an InGaAsP/InP active region. A carrier-confining structure was formed on the active region before the top mirror was bonded to the sample. These VCSOAs show the highest fiber-to-fiber gain (17 dB) and the lowest noise figure (6.1 dB) of any long-wavelength VCSOAs to date. VCSOAs should find applications as low-cost, single-channel amplifiers, amplifying filters, amplifying switches or modulators, as well as in two-dimensional array applications such as optical interconnects. We demonstrate the use of VCSOAs for optical preamplification at 10 Gb/s. Using an 11-dB gain VCSOA, the sensitivity of a regular p-i-n detector was increased by 7 dB resulting in a receiver sensitivity of -26.2 dBm.

Mineral admixtures in mortars: Effect of inert materials on short-term hydration

This work is the first part of an overall project the aim of which is the development of general mix design rules for concrete containing different kinds of mineral admixtures. The separation of the different physical effects responsible for the modification of cement hydration, when chemically inert quartz powders are used in mortars, is presented. The phenomenological approach, based on semi-adiabatic calorimetry, is only associated with first-order phenomena, and the study excludes the complex physicochemical details involved in the chemistry of cement. The results, obtained for a wide range of fineness (between 180 and 2000 m 2/kg) and replacement rates (up to 75%), show that short-term degrees of hydration in mortars containing a chemically inert mineral admixture (quartz) are always higher than for a reference mortar. This study confirms that cement hydration is enhanced by inert mineral admixtures. The two main physical effects responsible for the modification of the hydration of cement are identified as the dilution effect and heterogeneous nucleation. The dilution effect of the cement is highlighted with a coarse mineral admixture. The heterogeneous nucleation effect, although it increases with fineness of mineral admixtures, presents an optimum depending on the replacement rate. In the following part of this work, these results will be used for the development of an empirical model allowing us to quantify both physical effects.