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Mid-infrared (MIR) quantum cascade laser (QCL) frequency combs are an appealing technology for dual-comb spectroscopy as they cover strong absorption bands of many relevant molecules in the MIR region and enable measurements with sub-microsecond time-resolution permitting novel insights into dynamical processes [1] . The comb properties can be directly controlled through the QCL driving current, the chip temperature or by electrical injection of the repetition frequency [2] . Nevertheless, full mutual stabilization of a QCL dual-comb spectrometer (DCS) has not yet been reported. In this work, we demonstrate a DCS with full mutual stabilization in a master-follower (MF) scheme (also known as master-slave) and the coherent averaging of its signal.

In this paper, based on artificial neural network (ANN) a method is provided to estimate the long-term voltage stability margin. Reviews in this paper show that the amplitude of voltage nodes and phase angles are the best predictors for voltage stability margin. In addition, the paper shows that the proposed neural network-based methods successfully are able to estimate voltage stability margin in normal mode. If the voltage amplitude and phase angle in real time is obtained from phasor measurement units (PMU), in this case, using the proposed method, voltage stability margin can be estimated in real time and can be used to start actions related to stability control. Numerical examples of the proposed method are presented using IEEE 9-bus test systems.

Fatigue damage has always been a significant concern for engineers regarding offshore structures applications. This phenomenon is investigated, especially for lattice structures such as jackets in which tubular welded connections are the most critical points threatened with fatigue failure. Fatigue damage, moreover, for jacket-type offshore wind turbines have relatively been examined in literature focusing on structural considerations. However, since most offshore wind turbines simulation programmes use simplified soil-pile interaction models such as Apparent Fixity model; fatigue analyses concerning such models, especially the Apparent Fixity model, have not been investigated so far. More specifically, the impacts of different apparent fixity lengths on fatigue damage in jacket-type offshore wind turbines have not been taken into account. In this study, fatigue analysis of the jacket-type offshore wind turbine supported by "Upwind" reference jacket for different pile fixity lengths is carried out considering both wave and wind loads applied on the structure. Apparent fixity model is used herein for soil-pile interaction. Ultimately, a sensitivity analysis for fatigue damage to different pile fixity lengths is carried out in order to find how accumulated fatigue damage is changed. It is concluded that fatigue life of a connection -the most vulnerable one to fatigue damage - in jacket substructures of the offshore wind turbines is considerably sensitive to pile fixity length when applying Apparent Fixity model for soil-pile interaction.

Study of the structured-ness of Quranic surahs has attracted the attention of some researchers in recent years. One of the theories herein is the theory of Topic Sameness which acknowledges that the inner elements of surahs have tight relationship with each other and that each surah of Quran has formed on a single core topic. In this paper, we intend to study the topic sameness in Quranic surahs using natural language processing methods. In this regard, based on the two methods of word2vec and Roots' accompaniment in Verses, the similarity of Quranic roots is calculated. Then, the amount of similarity between surahs' title and the concepts within the surahs is studied. Afterwards, the amount of similarity of the concepts within chapters to each other is calculated and compared with the random mode. The results show that the choice of the surah's title is based on rational logic, and that could not have been done by the ordinary public of the early Islamic era. In addition, the surahs hold the inner coherence between the concepts so that they have formed on a single topic or a few topics tightly related to each other.

Paraphrase detection is one of the fundamental tasks in natural language processing. Designing a system to detect the paraphrase pairs requires a good understanding of different feature extraction methods. To tackle this challenge, lots of work have been done to extract various types of features. Knowing which types of features are discriminant for paraphrase identification, saves a lot of time for researchers and helps them obtain better result in their works. In this paper we compare various types of feature extraction methods that neither need any prior knowledge nor any external resources, so they can be used in every language. Our experiments show that those types of methods which specify the importance of each word in documents or break down the document into specific parts, have a better result compared to those methods that try to capture the meaning of a given document as a whole and treat the document as a single component.

In recent years, due to increasing use of electrical apparatuses, industrial needs for electricity, flexibility of electrical energy and its easy production and distribution, this energy has been called the superior energy. Because of energy security, lack of fossil fuels and global concern for environmental pollution, renewable energy sources are used to generate electrical energy. The sun is the most important source of renewable energies. The average amount of solar radiation to Earth's surface is 8000 times higher than the average energy consumption in the world. According to the amount of solar radiation emitted by the sun to the Earth's surface, per capita of this energy is 20MW. Solar cells are no-noising devices that do not pollute the environment. Due to the lack of moving parts, these equipment have been become a powerful, reliable, lifelong tool. For the reasons mentioned, the use of solar cells is increasing day by day. At the moment, the cost of designing and installing solar systems is high. But these costs are predicted to decline in the future. In this article, the authors have tried to provide a comprehensive overview of the factors affecting the installation of solar cells, such as the location of the installation site and the solar parameters.

Human activity monitoring has become widely popular in recent years, and has been utilized in a vast number of fields and applications. Most of the activity recognition algorithms proposed have emphasized the use of inertial sensors in smartphone devices or other bodily-worn sensors. However, wearable inertial sensors are not interactive, and smartphones are not easily worn. Thus, with the advancement of smartwatches, unique opportunities exist to provide user interaction and highly accurate personalized activity recognition. Through the use of Active Learning, an interactive machine learning technique, specific behaviors can be learned by querying for unknown actions. This paper describes a smartwatch-based active learning method for activity recognition to identify 5 commonly performed daily activities. The results of this study revealed that this system can obtain a 93.3% accuracy across 12 participants. From our results, we demonstrate that an interactive learning approach using active learning in smartwatches has significant advantages over smartphones and other devices for activity recognition tasks.

Quantum cascade lasers (QCLs) are powerful semiconductor light sources, based on intersubband transitions, which can be tailored to operate in the mid-infrared (MIR) region of the electromagnetic spectrum [1]. This region is of particular interest for applying various gas absorption spectroscopy schemes, as many of the characteristic transitions of several gas molecules occur at energies that are situated in this region [2].

We present a digital-to-time converter (DTC)-assisted fractional-N wide-bandwidth all-digital PLL (ADPLL). It employs a MASH ΔΣ time-to-digital converter (TDC) to achieve low in-band phase noise, and a wide-tuning range digitally-controlled oscillator (DCO). Fabricated in 40nm CMOS, the ADPLL consumes 10.7 mW while outputting 1.73 to 3.38 GHz (after a ÷2 division) and achieves better than −109 dBc/Hz in-band phase noise and 420fs rms integrated jitter.

We propose a new transmitter architecture for ultra-low power radios in which the most energy-hungry RF circuits operate at a supply just above a threshold voltage of CMOS transistors. An all-digital PLL employs a digitally controlled oscillator with switching current sources to reduce supply voltage and power without sacrificing its startup margin. It also reduces 1/f noise and supply pushing, thus allowing the ADPLL, after settling, to reduce its sampling rate or shut it off entirely during a direct DCO data modulation. The switching power amplifier integrates its matching network while operating in class-E/F2 to maximally enhance its efficiency at low voltage. The transmitter is realized in 28 nm digital CMOS and satisfies all metal density and other manufacturing rules. It consumes 3.6 mW/5.5 mW while delivering 0 dBm/3 dBm RF power in Bluetooth Low-Energy mode. European Research Council

Commonly, near field RFID is used in situations where a tag is brought close to some device that is to read the identity of the tag thereby enabling some action: unlocking a door, reading payment information at a merchant's register, or sharing social information between enabled devices. In all these cases, the ergonomics of the physical reading process can be hindered if read range requires a user to awkwardly maneuver the tag near the reader until a read is achieved. One way to facilitate an extended and reliable read range borrows on knowledge from the wireless power transfer community where it is known that increasing the Quality factor of the reader or tag coil will increase power transfer. However, RFID engineers have typically limited maximum coil Q factor to about 10–20 due to the need for maintaining a system bandwidth that is broad enough to support the necessary communication data rates. To meet this challenge, this paper introduces a method of impedance matching high Q reader coils to the source known as "over-coupling" the source to the system input. On one hand, the use of high Q coils extends the range where the tag receives sufficient power to turn on, while it is over-coupling that slightly damps the system resonance, producing an effective system Q factor that simultaneously supports a bandwidth wide enough to accommodate necessary data rates. This work will show both theoretically and through experimentation that using high Q coils in the over-coupled regime supports extension of read range in near field RFID systems by 81% or more compared to the next best impedance matching strategies.

We examine a new approach to finding efficient routing paths in large networks (e.g. inter-datacenter networks). Such networks carry many simultaneous data transmissions and efficient routing paths need to be found for each transmission. One way this problem can be solved is by first finding a multi-commodity flow solution for all source-sink pairs. This provides traffic flow information for each connection but does not specify specific routing paths to use. We consider the problem of decomposing these flow solutions into a small numbers of routing paths. The specific problem we consider is the following: Given a flow with source and sink nodes s and t, we wish to exactly represent the flow as the sum of a small number of path flows. In this work, we describe a novel approach to finding good flow decomposition solutions using parity balancing path flows. We present two new algorithms termed OddCover and JointOddCover that provide theoretical performance guarantees and are effective in practice. Our experimental results demonstrate that the proposed algorithms are competitive with the best heuristic approach.

This paper proposes a new RF oscillator topology that is suitable for ultra-low voltage and power applications. By employing alternating current source transistors, the structure combines the benefits of low supply voltage operation of conventional NMOS cross-coupled oscillators together with high current efficiency of the complementary push-pull oscillators. In addition, the 1/f noise upconversion is also reduced. The 40nm CMOS prototype exhibits an average FoM of 189.5 dBc/Hz over 4–5 GHz tuning range, dissipating 0.5mW from 0.5V power supply, while abiding by the technology manufacturing rules.

The 1/f (flicker) noise upconversion degrades the close-in spectrum of CMOS RF oscillators. The resulting 1/f3 phase noise (PN) can be an issue in PLLs with a loop bandwidth of m -device drains [2] have shown significant reduction of the 1/f3 oscillator PN corner. However, the former needs an additional tunable inductor and the latter degrades PN in the 20dB/dec region.

This paper presents a CMOS temperature sensor intended for the temperature compensation of MEMS frequency references. It is based on a Wien bridge RC filter, whose phase-shift, due to the temperature dependency of the resistors used, is temperature dependent. This phase shift is then digitized by a phase domain sigma-delta modulator. The sensor was implemented in 0.18μm CMOS, consumes 36 μW and achieves 6mK resolution in a conversion time of 100msec. After batch calibration and a 3-point trim, it achieves ±0.15°C (3σ) inaccuracy over the industrial range (-40°C to 85°C).

The 3G systems such as LTE as well as 4G systems will employ Multiple Input, Multiple Output (MIMO) transmission scheme based on OFDM (Orthogonal Frequency Division Multiple access) techniques. The LTE (Long Term Evolution) standard widely uses the MIMO-OFDM structure to improve downlink peak rate, cell coverage, as well as average cell throughput. In this paper, first, the performance of the SFBC (Space Frequency Block code) in MISO (Multiple Input Multiple Output) and MIMO channels are compared with SISO (Single Input Single Output) channel, and then performance of these two scheme, in frequency selective MIMO channel, in varying amount of correlation coefficient between uniform linear array antenna elements in transmitter and receiver, is checked. in this paper, simulation results show that the SFBC has a great impact on improving BER in low SNR whereas VBLAST (Vertical-Bell Laboratories Layered Space-Time) improve data rates in high SNR; also in both scheme, in environments with low correlation between antenna elements, with sufficient spacing between antenna elements, performance is improved.

In this paper, the voltage stability in power systems with economic dispatch (ED) problem is investigated. Also because of increasing the number of wind generators in power systems, they are considered in this investigation. For this purpose, with ED equations and equality and inequality conditions, a voltage stability index is considered. This index is considered as an inequality condition by optimization problem to guarantee the voltage stability in addition to economical optimization. Special conditions of wind generators are investigated too. Because of the complexity of this problem, harmony search method is used for solution of this optimization problem. Simulation results are presented to examine the performance of this method.

For the first time we demonstrate the existence of a turnover temperature in extensional-mode silicon microresonators, fabricated on highly n-type doped substrates and aligned to the [100] crystalline orientation. This behavior is commonly observed in quartz resonators and is a key to achieving exceptional temperature stability in oven-controlled crystal oscillators. In order to show the effect of doping concentration and resonator alignment to different crystalline orientations, the thin-film piezoelectric-on-silicon (TPoS) platform is utilized. It is shown through both theoretical analysis and finite element simulation that the turnover temperature is a function of doping concentration and orientation. In order to experimentally validate this result, similar resonators are fabricated on silicon-on-insulator (SOI) substrates and the temperature variation of frequency is measured. The trends are shown to agree with theory. An overall temperature-induced frequency variation of less than 150ppm is measured over the range of −40 to 85°C for a ∼25MHz TPoS resonator aligned to the [100] plane; this shows more than 24 fold reduction with respect to the uncompensated conventional silicon resonators reported before. Our work is a significant step toward strengthening silicon's position as an alternative resonator technology in the quartz-dominated stable oscillator market.

Simply stated, energy hub is a unit which receives different energy carriers such as electricity, natural gas and heat in its input and after some energy converting or storing, delivers the required energy in its output. Considering unique features of energy hubs, these units are of a great concern in many European industrial countries recently in order to supply their energy loads economically. In this case, selecting and commitment of different possible units inside the hub structure and also quality of their operation are one of the most significant problems. In this paper, a completely linear method for simultaneous structural and operational optimization of energy hubs is proposed for multi period given loads and energy costs. Finally the proposed method is used for structural and operational optimization of a hub in order to supply a 24-hour energy load. Obtained results confirm the optimality of using energy hub and proposed method for supplying required loads especially in presence of energy storage elements.