A wideband stepped-impedance rectangular-ring resonator bandpass filter with multiple notched bands

A configuration of wideband bandpass filter (BPF) with multiple notched bands is presented. Proposed BPF is based on stepped-impedance resonator. By utilising dual stepped-impedance resonators in folded topology a rectangular-ring resonator is formed. Two notched bands in the passband are achieved without using asymmetrical coupled lines. In other words, the filter configuration is capable of producing notched bands. It should be noted that additional information on filter performance and design is presented. Measurement results are presented to approve propounded filter characteristics. The measured passband of the second proposed filter is from 3.68 to 10.2 GHz with insertion loss of –1.76 dB in the first passband at the centre frequency of 4.45 GHz. The measured notched band frequencies are about 5.45 and 7.95 GHz with rejection of –21.77 and –20.82 dB, respectively. The return loss in the passband is better than –11.4 dB.     

Characteristic Drying Curves of Cocoa Beans

ABSTRACT

The characteristic drying curves of cocoa beans are determined by using a tunnel drier where conditioned air passes a single cocoa berm suspended from an electronic balance in the test section. Weight loss, and temperatures of air, testa and nib of the cocoa bean is monitored on personal computers. The nornmalised drying rate versus the normalised moisture content is regressed by least square method to fit a new polynomial model for the penetration falling rate period and a linear model for the regular regime falling rate period. It can be concluded that there are three drying periods for cocoa beans namely the constant drying rate period, the penetration falling rate period and the regular regime falling rate period. The polynomial model estimates the penetration period quite well whereas the linear model estimates the regular regime quite well as well. There is no observable influence of relative humidity and air temperature on the characteristic drying curve of cocoa beans. However, the air velocity seems to have some influence on the curve.     

A novel configuration for UWB LNA suitable for low-power and low-voltage applications

Two UWB LNAs based on a new configuration suitable for low-power and low-voltage applications are presented. The proposed configuration saves bias circuit because of sharing only a bias circuit. In designing LNA-1 good phase linearity property achievement is followed for low-power and low-voltage applications, while in LNA-2 the main concerns are high power gain, by keeping low-power consumption, and small chip area. By taking advantages of resistive-feedback and RLC load, wideband input matching is obtained. Based on the proposed configuration, accompany with complete noise analysis, noise of LNA-2 is highly suppressed and flat noise figure is reaped. The 130 nm CMOS LNA-1 and LNA-2 dissipate 2.95 mW and 6.09 mW, respectively, from 0.7 V supply voltage, without using of forward-body-bias technology. Input return loss of both LNAs is below than ?10.5 dB while LNA-1 achieves average power gain of 9 dB and LNA-2 17 dB. The group-delay variation of LNA-1 is about ±6.1 ps over the band of 3.1–10.6 GHz. The NF of LNA-2 is 2.4–2.89 dB over the whole band of interest.     

Arch growth after staged repair of interrupted aortic arch using carotid artery interposition

BACKGROUND: Between 1980 and 1990, our practice was to perform carotid artery interposition as part of a staged repair of interrupted aortic arch with various associated cardiac defects. METHODS: This procedure was used in 16 patients with IAA type B. The median age at operation was 4.5 days and the median weight, 3.2 kg. Ten of the patients had an associated ventricular septal defect. Six more had complex anatomy. There were two death at carotid interposition, two interim deaths, and two deaths after intracardiac repair. Preoperative echocardiographic and angiographic studies were compared with postoperative studies in 11 survivors of arch repair to assess sequential growth of the interposed carotid artery. Measurements of the carotid artery were normalized to the descending aorta. RESULTS: Preoperatively, the left carotid artery had a median diameter of 3.7 mm and was 42.9% of the descending aortic diameter. Postoperative studies performed at a median age of 5.7 months disclosed that the interposed carotid artery had grown to a median diameter of 7.0 mm and was 69.6% of the diameter of the descending aorta (normal > or = 81%). On follow-up at a median time of 4 years, 6 of 9 patients have no gradient by blood pressure measurements or echocardiographic Doppler studies, and 3 have modest gradients. No patient has required revision of the arch repair. CONCLUSIONS: Survival is good after carotid artery interposition for interrupted aortic arch and growth of the carotid artery approaches that of a normal arch. Carotid artery interposition is a viable alternative for repair of this lesion should primary definitive repair not be feasible.     

Analysis of Ordered Categorical Data Using Expected Loss Minimization

Robust design is a strong method for the quality improvement of processes (or products). Two main techniques for data analysis in robust design process are the S/N ratio technique and accumulation analysis developed by Taguchi. Accumulation analysis is developed for the study of ordered categorical data. In this article, the current techniques are studied. Then, a new method that is more accurate than other methods is developed and introduced. In the next phase, an example from literature solved by the methods and the new method's optimality against other methods is shown.     

Sustained oscillations in MIMO nonlinear systems through limit cycle shaping

This paper studies on generating periodic behaviors through shaping stable limit cycles in multiple‐input‐multiple‐output nonlinear systems. For this purpose, first, limit cycles are shaped with respect to the desired sustained oscillations of the system's outputs. Then, the Lyapunov analyses, which are appropriate for stability analysis of invariant sets, are employed to design the control law and conclude the asymptotic convergence toward the predefined limit cycles. The problem is studied in two cases. In the first case, some assumptions in the mathematical model are assumed that leads to simplification in the design procedure. In the second case, the design procedure is discussed in more general cases. Finally, the validity and performance of the proposed method for shaping limit cycles with different geometric shapes are illustrated by computer simulations for practical and numerical examples.     

Rhéologie des murs en blocs de terre comprimée en compression uniaxiale: étude et modélisation

Static uniaxial compression tests have been conducted on samples of small walls made of compressed earth blocks. These tests permitted to determine, besides the compression strength, other parameters, namely Young’s modulus, the limit strain and Poisson’s ratio. To predict the mechanical behaviour of small earth-block walls, a non linear model based on the theory of elasticity-damage coupling is proposed. Indeed, this model has been applied for the block and the mortar. While confronting the experimental results with those of the model, the model proves to be satisfactory. The residue of approximation is under 10%. The model is intermediate between the two limit models proposed for the heterogeneous materials, namely Voigt’s and Reuss’. The determination by the model of the damage ratio gives information on the evolution of the damage within the walls according to the applied loading.     

An Equivalent Circuit Model for Broadband Modified Rectangular Microstrip-Fed Monopole Antenna

A new, simple equivalent circuit model for designing a multi-mode/broadband modified rectangular microstrip-fed monopole antennas using stepped cut at four corners (SCFC) method has been presented in this paper. The SCFC method is a method in which the four corners at the edges of the patch are cut for the purpose of designing the microstrip-fed monopole antenna. The design procedure of a single mode to a broadband microstrip-fed monopole antenna is explained in order to help understand more about the proposed equivalent circuit model and SCFC method. The computer simulation technology (CST) microwave studio and advanced design system (ADS) software are used to design and simulate of the proposed microstrip-fed monopole antennas and their equivalent circuit model, respectively. The operating bandwidth of the broadband antenna with \(\hbox {S}_{11}< -10\) dB, covers the operating frequency range from 0.9 to 2.6 GHZ that it is suitable for GSM (0.9 GHz), WiFi (2.4 GHz) and LTE (2.6 GHz) applications. For the purpose of validating the simulated results, the antennas prototype has been fabricated and measured. The comparison of the measurement and simulation results shows that, there is a good agreement between them.     

Migration Issues and Strategies for Token Ring

This article considers the problems caused by ever increasing traffic on Token Ring LANs. It shows how the new IEEE 802.5 standard for DTR addresses this problem, outlining scenarios and providing a migration strategy for evolving networks, using this new standard. © 1997 John Wiley & Sons, Ltd.