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This paper addresses a method for devising an undamped periodic structure that suppresses energy propagation due to a specific wave mode based on the Wave and Finite Element (WFE) method. Then, structural modifications to reduce the active transmitted power are derived by solving an inverse eigenvalue problem of the WFE method. In solving the inverse problem, it is important that the solution is feasible in the sense that it is low-cost and easy to fabricate as an actual mechanical structure. Therefore, in the proposed method, the designer specifies the regions in which structural modifications may be made before solving the inverse problem. As a result, the solution of the inverse problem is approximated within these regions. Finally, the method allows us to suggest feasible structural modifications necessary to reduce the amount of active transmitted power for a given wave mode and a given frequency. However, this method cannot consider the changes in wave numbers due to structural modification. It should therefore be noted that this method cannot be used to achieve significant reductions in active transmitted power due to large-scale structural modification.

The article considers the issues of possible using tethered telecommunication platforms on the base of unmanned aerial vehicles (UAV) for signal retranslation of ground robotic complexes (RTC) control when performing emergency rescue operations in emergencies. The relevance of the topic is due to the need to find ways to protect the RTC control system from the negative effects of powerful heat sources in case of fire, ionizing radiation and numerous interferences arising from dense urban development, when the operator must be removed from the complex at a considerable safe distance.

The presence of metallic structures with array of slits, when slits have dimensions much less than the wavelength of the incident optical wave, typically causes extraordinary power transmission. This excellent power transmission indeed comes from the surface waves on the periodic structure excited by the transverse magnetic wave. Here we show that if slits are stepped, then the incident wave power is transmitted into the substrate at desired optical frequency entirely and simultaneously in terahertz frequency band by 70%, for I n 0.53 G a 0.47 A s substrate. Power transmitted through the proposed structure is derived both in a closed form by an analytical model as well as numerically by finite element method. It is found that with the increase of field intensity in the substrate, the structure with array of stepped slits (as opposed to uniform slits) favorably has no reduction of frequency range at maximum transmitted power. [ABSTRACT FROM AUTHOR]

Sistemler için birçok güç tanımlamaları yapılmıştır. Farklı güç tanımlamaları ve bileşenlerinin doğru bir şekilde hesaplanması ve ölçülmesi son derece önemlidir. Bu amaçla çok sayıda yöntemler ve teknikler geliştirilmiştir. Gerçekleştirilen çalışmada; literatürde tanımlanan gelen-yansıyan-iletilen güç bileşenlerinin geleneksel Fourier dönüşümüne alternatif olarak dalgacık paket dönüşümü kullanılarak hesaplanması önerilmiştir. İlgili güç analizlerini yapmak için etkileşimli grafiksel arayüz programı tasarlanmış; önerilen hesaplama tekniğinin etkinliği ve doğruluğu, gerçekleştirilen benzetimlerle/uygulamalarla gösterilmiştir.

Abstract Low delay and long lifetime are a very important issue for industrial wireless sensor networks (IWSNs) in which it require long-time monitoring of industrial sites and respond quickly to events that is monitored; therefore, high delay communications can cause serious damage to property and personnel at industrial field. Due to delay, lifetime, and other performance involved to multiple layers, it is difficult to optimize from a single layer. Therefore, a cross-layer design optimal scheme for reducing delay and maximizing lifetime (RDML) scheme is proposed for IWSNs which is from several layers such as transmitted power, duty cycle, and node deployment positions to optimize the network performance of delay and lifetime etc. Firstly, due to the node which sends a packet within a cycle, different duty cycle leads to different selection of the modulation level, resulting in different power consumption efficiency of transmitting data. Through careful analysis, the optimal value of the duty cycle is given which has the lowest energy consumption per bit. In fact, the energy consumption of the node is not balanced. Therefore, an optimization method of changing the duty cycle is proposed. In this paper, larger duty cycle is chosen for nodes with residual energy to improve the reliability of data transmission, reducing the probability of data retransmission, so that the network delay can be reduced in IWSNs. Third, based on the previous analysis, a network optimization deployment algorithm is proposed, which not only maximizes the energy efficiency of a single node but also maximizes the network lifetime and the total network energy efficiency. Both our comprehensive theoretical analysis results indicate that the performance of RDML scheme is better than the previous studies. Relative to equal distance and optimal duty cycle scheme, the RDML scheme can reduce the delay by 19–30% and increase the lifetime by more than 43%.

In this project, the main focus is to enhance the existing power control algorithm that is applied in a single cell of CDMA network. Nash algorithm is selected and is further improved with modification of its cost function with a value as power of target SINR, which to reduce the SINR error at first iteration, so as to increase the rate of convergence effectively. Decision of a value is important to ensure the SINR error is reduced at first iteration. The uniqueness and algorithm convergence of enhanced cost function is proven with certain conditions requirements. Therefore, enhanced Nash algorithm (ENA) is proposed which only applicable in first iteration of power control method. The rest of iterations are applied by Nash algorithm due to its better convergence to target SINR. After simulations, with consideration of Rayleigh and Rician fading channels, a significant increase in rate of convergence while maintaining the SINR with error less than 0.01 is shown. The transmitted power is lower in some scenarios, or with very slight reduction less than 0.5%. The SINR error at first iteration is reduced about 20% more by using ENA. In overall, ENA has better performance than the existing Nash algorithm in terms of transmitted power and rate of convergence, without compromising SINR. [ABSTRACT FROM AUTHOR]

We present an open-aperture elliptic Gaussian beam Z-scan theory for thin nonlinear optical material possesses simultaneous N - n nonlinear absorption processes with residual linear absorption. We show that an approximate analytical but closed-form expression for the normalized energy transmittance is possible by means of the weak nonlinearities approximation. The elaborate theory can be used to fit the open Z-scan traces allowing the determination of material's nonlinear absorption coefficients and incident Gaussian beam parameters. The contribution of absorptions of distinct order can also be identified, separated and compared. [ABSTRACT FROM AUTHOR]

A uniform fiber Bragg grating sensor is sketched and inspected by the finite-difference time-domain method in furtherance of obtaining ultimate transmission and reflection spectra by optimizing the FBG parameters like refractive index, grating height, grating width, wafer width, wafer length. The maximum transmission power spectrum is achieved as − 7 dB for the refractive index of 3.005, and the maximum reflection spectra are obtained as 6 dB for the grating height of 1 μm which is enhanced nine times than the precedent work. The proposed FBG is a simple, light-weight, low-cost uniform structure, and it offers high reflectivity and ease of handling. Therefore, it is highly useful in sensing and communication applications. [ABSTRACT FROM AUTHOR]

The idea of ‘energy router’ (ER) is put forward as a critical application of the energy Internet (EI), especially in the new generation of electric power system to fulfil the power management and to deal with the integration of massive distributed generations. Furthermore, AC/DC hybrid network becomes a kind of development trend since it can improve the power quality and efficiency compared with adding converters for DC loads. This article proposes a decentralised control method for multi-port converter (MPC)-based ERs to achieve flexible power regulation and ‘plug and play’ operation. With the proposed schemes, DC bus voltage can be maintained together by multi-ER through appropriately adjusting their transmitted power according to the pre-set power-sharing ratio. Furthermore, the sharing ratio can be online changed for flexible power regulation. The stability of the system is ensured by Lyapunov method, detailed simulation results are presented to validate the feasibility of the proposed scheme under different operating conditions.

We present a theoretical analysis of multi-photon absorption processes. We find an approximate closed-form expression of the normalized transmittance for a thin sample with two successive nonlinear absorption processes at a time (n - and (n + 1) -photon absorption) in the presence of residual linear absorption. Our approach allows for simultaneous identification and evaluation of the nonlinear absorption coefficients and Rayleigh lengths of the incident elliptic Gaussian beam by fitting the open Z -scan traces. [ABSTRACT FROM AUTHOR]

With the new IEEE 802.11ah standard aimed at improving the existing WLAN standard for the machine-to-machine applications, there is a renewed interest from the research community to analyze and suggest improvements to the standard. With thousands of smart devices and sensors involved in an internet of things network, the interference from multiuser access becomes a serious issue. This paper presents an access point (AP) coordinated multiuser access mechanism for such applications, where the strategy to improve channel usage efficiency is based on analyzing interference present in the neighborhood. Interference experienced in such a system is a function of node location, transmitted power, traffic load and resource allocation. In our proposed system, each WLAN AP from the overlapping basic service sets employs multiple frequency sub-bands and associates user nodes to these sub-bands dynamically. We show that this proposed interference-aware dynamic frequency allocation (IDFA) scheme, which is based on neighborhood contention analysis, can significantly enhance the system throughput and improve the energy efficiency by about 30%. In dense user node deployments, the channel access efficiency of the IDFA multi-band scheme is 2–3 times higher than that of the single band legacy WLAN. [ABSTRACT FROM AUTHOR]

• Derive an analytical model for calculating electromagnetic power transmitted through nano-scale structure with periodic stepped slit into substrate. • Design a new periodic metallic structure that is capable of transmitting electromagnetic power entirely at λ = 0.8 μm into LT-GaAs. • Confirmation of the analytical model results by FEM results within COMSOL multiphysics software. • Explain application of the designed structure in increase of THz radiation power of plasmonic photoconductive antennas (PCAs). Metallic structures with periodic array of subwavelength slits are well-known to lead to extraordinary optical transmission (EOT). Excellent power transmission originates from surface waves excited by incident transverse magnetic wave. Here we show that the metallic structure with array of three-stepped slits can transmit almost the entire power of incident wave into the substrate at desired optical frequency for low-temperature-grown gallium arsenide (LT-GaAs) substrate. Transmitted power of the proposed structure is studied both by an analytical model as well as numerical method by finite element (FEM). It is found that existence of three corners in the proposed structure can favorably confine generated carriers in the vicinity of the electrodes as this structure is used in photoconductive antenna (PCA); this feature contributes to increase terahertz (THz) current and subsequently THz radiation power of PCAs. [ABSTRACT FROM AUTHOR]

Reflected signal levels in passive RFID require seperate TX and RX antennas to overcome the reader threshold. Using latest improvements, it is shown in this work that both the forward and backward links restrict communication distance given with equations depending upon tag power dissipation, antennas in use, type of modulation and operating environment and parameters to make both distances equal are given. Complete link budget for the forward and backward links in a RFID system are given with constituent parts in detail. After that, to further elaborate on the link budgets, reflection coefficient and power equations are obtained from a RFID front-end model with circuit theory and shown on a passive RFID system. This study shows modulation index m and antenna gain Gt for BPSK and ASK modulations to make two distances equal for the environment to be within, found from two way link equations. Also, ASK and BPSK modulations are compared on communication distance for given average backscatter difference power, minimum SNR to targeted BER on the reader by the equations obtained on the circuit model and MATLAB simulations. [ABSTRACT FROM AUTHOR]

Incident power has an important effect on the optical transmission properties of magnetic fluids. Difference in the effect of the incident power on the optical transmission properties with and without an applied magnetic field was investigated by measuring the transmitted power of the incident light through the magnetic fluid film. In the absence of an applied magnetic field, an approximately linear relationship exists between the incident power and the transmitted power of magnetic fluid films, but the relationship is nonlinear when a magnetic field is applied. Moreover, variation in the optical transmission properties under a magnetic field with various incident powers was measured in experiment. As the magnetic field is enhanced, the transmitted power of the magnetic fluid film first decreases, then increases, and finally reaches saturation. The magnitude of the change in the transmitted power, and the magnetic field range correspond to decreases, increases and saturation are related to the incident power. Therefore, for the sensing applications, depending on the measuring range of the magnetic field and the required variation range of the transmitted power, magnetic fluid film sensors exhibit different characteristics if different incident power values are selected. [ABSTRACT FROM AUTHOR]

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Objectives: In this article, we seek to determine how sensitive road cyclists are to vertical vibration transmitted while riding a road bicycle and to propose metrics for the evaluation of dynamic comfort.Background: Road cyclists are exposed to random-type excitation due to road roughness. Vibration transmitted affects dynamic comfort. But how sensitive are cyclists to vibration level? What are the best metrics to measure the amount of vibration transmitted to cyclists? Previous studies used sinusoidal excitation with participants on rigid seats and measured acceleration.Methods: We use a psychophysical estimation of Just Noticeable Differences in Level (JNDL) for vertical vibration transmitted to cyclists on a road simulator. In Experiment 1, we estimate the JNDL for whole-body vibration using vertical excitation on both wheels simultaneously (20 male cyclists). In Experiment 2, we estimate the JNDL at two different points of contact by applying the same signal to only the hands or the buttocks (9 male cyclists).Results: The JNDLs are expressed in terms of acceleration and power transmitted to the cyclist. We compare the JNDLs expressed with these 2 metrics and measured at different points of contact.Conclusion: Using these two metrics and at all points of contact, vibration magnitude needs to be reduced by at least 15%, for the change to be detectable by road cyclists.Application: A road bicycle needs to transmit at least 15% less vibration for male cyclists to detect an improvement in dynamic comfort. Dynamic bicycle comfort can be measured in terms of a new metric: power transmitted to the cyclist. [ABSTRACT FROM AUTHOR]

The authors present here designs for tuneable confined Tamm plasmons (CTPs) resonant at 1.3 μm, consisting of an AlAs/GaAs distributed Bragg reflector and gold disc. Using numerical methods they explored the effect of disc diameter on the CTP resonance and position of a dipole source (modelling a quantum dot) on emission through the disc. They found decreasing disc diameter resulted in a blue‐shifted fundamental mode and that a dipole positioned at the centre of the disc emitted with an angular distribution that collected 90% of the transmitted power within a numerical aperture of 0.7. They also explore the Purcell enhancement under the CTP as a function of dipole position. [ABSTRACT FROM AUTHOR]

This paperwork examines the problem of maximum power transfer to the load of a long line mode change from idle line (XX ) to short-circuit ( SC). Load line changes from idle mode (IM ) to its short-circuit (SC ). The line length varies from zero up to a length equal to the physical length of the electromagnetic wave. As a method of research it is used the method of the complex amplitudes (MCA). As independent variables were examined her load line length and that the system per unit change in the band plus minus unit to unit , so . It enteritis that for the active character load of the active power input and power output of the line, so functions , and functions that characterize developments efficiency , power factor at the input line and the load power factor when the variable z. For these points to the notion of critical value of the load . It founds the effect of " recession " critical resistance values and functions şi , which is not found for the other functions considered - efficiency and power factor. Load reactive power compensation can help to increase power output only for lines with length smaller than ¼ wave length electromagnitice wave. In non-distortional lines, such effect is not observed. The paper work represents the general data transmission mode the maximum power lines of different lengths to the load, which varies from idle mode (IM) to short-circuit (SC) regime. These data can be used for preliminary analysis of the efficiency of the electrical lines at variable load.

Performance of waveguides for long-distance energy transport in microwave heating was evaluated by comparing the microwave propagation characteristics, including maximum transmitted powerPtrans, attenuation constant α and percentage of power lossplossproposed in this study, of commercially available rectangular waveguides (WRs) constructed of various metals (Ag, Cu, Ag, Al and Fe) for microwave heating at 0.915 and 2.45 GHz with those of different types of circular waveguides, namely circular waveguides with the same cut-off frequency as rectangular waveguides (denoted by WCFs), circular waveguides with the size equal to rectangular waveguide (denoted by WCDs), and circular waveguides with the same circumference as rectangular waveguides (denoted by WCCs). It is demonstrated that WCFs exhibit the highest values of maximumPtranstogether with lowest α andplossdue to their characteristics of microwave field configuration. Circular waveguides (e.g. WCF1150) made of Cu or Al with large dimensions operating at 0.915 GHz are suitable for microwave heating through long-distance microwave energy transport over the distance compared to traditional rectangular waveguides, with up to ∼50% reduction of power loss. Optimal waveguides for long-distance uses can be obtained by assessing microwave propagation characteristics together with manufacturing cost, depending on specific applications. [ABSTRACT FROM AUTHOR]

We propose two novel designs of compact, linear, and all-optical OR and AND logic gates based on photonic crystal architecture. The proposed devices are formed by the combination of the ring cavities and Y-shape line defect coupler placed between two waveguides. The performance of the proposed logic gates has been analyzed and investigated using finite difference time domain method. The suggested design for AND gate offers ON to OFF logic level contrast ratio of not less than 6 dB and the suggested design for OR gate offers transmitted power of not less than 0.5. On top of that, the proposed OR and AND logic gates can operate at bit rates of around 0.5 and 0.208 Tb/s, respectively. Further, the calculated fabrication tolerances of the suggested devices show that the rods radii of the ring cavities need to be controlled with no more than ±10% and ±3% fabrication errors for optical OR and AND gates, respectively. It is expected that such designs have the potential to be key components for future photonic integrated circuits due to their simplicity and small size. [ABSTRACT FROM PUBLISHER]

This article presents a linear power division algorithm to achieve almost constant modulated stimulated Raman scattering power. This assumes a linear variation of power in a channel with respect to another, which is a result of experimental verification. During this study, variation of signal power from 1 to 60 mW was done, and the number of channels varied from 3 to 99. [ABSTRACT FROM AUTHOR]

In this letter, pump power depreciation due to photodarkening effects in an ytterbium doped fiber (YDF) is investigated. Photodarkening is monitored by measuring the transmitted power at visible and pump wavelengths simultaneously, which renders direct quantitative measurement of pump power reduction rather than excess background loss. Our observation of substantial reduction in the pump power and the shortened fluorescence decay time in the photodarkened fiber indicates that the photodarkening influences pump efficiency. The effect of the photodarkening in a device level is also investigated by observing the performance of the YDF amplifier implementing the same YDF. The pump power depreciation of this fiber amplifier is quantitatively investigated by numerical simulation. The results suggest that operating at a saturated regime helps to subdue the photodarkening, with explanation in terms of population inversion density provided. The level of power depreciation is calculated to be 15%-30%, which matches our experimental observation. [ABSTRACT FROM PUBLISHER]

In this paper, we investigated specific properties and features of several kinds of Y-splitters based on gold nanorings arrays which are surrounded by SiO2 host substance, to be used at C-band spectrum (γ ~ 1550 nm). The comparison between two kinds of splitters shows that the symmetric splitter demonstrates better performance than the asymmetric splitter at given wavelength with high efficiency and transmittance (power ratio). Calculations proved that the transmitted power percentage was approximately ~47.5% in the well-organized splitter. It is shown that the offset distance plays an important role in the quality of the optical energy division and transmission through the plasmonic waveguide. The influence of increasing and decreasing in the offset distance was demonstrated numerically by snapshots. Hence, choosing and determining the appropriate value for the offset distance lead to the structure with lower losses and higher percentage in energy transmission. Ultimately, the optical behavior of an asymmetric nanostructure with unequal distances between the arms and the main array is investigated and its applications and possible purposes are introduced. [ABSTRACT FROM AUTHOR]