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The purpose of this paper is to investigate the thermal convection inside a spatially modulated domain.

The governing equations are mapped onto an infinite strip, allowing Fourier expansion of the flow and temperature in the streamwise direction.

Similar to Rayleigh‐Benard convection, conduction is lost to convection at a critical Rayleigh number, which depends strongly on both the modulation amplitude and the wavenumber. The effect of modulation is found to be destabilizing (stabilizing) for conduction for relatively large (small) modulation wavelength. Oscillatory convection sets in as the Rayleigh number is increased.

This paper presents novel results.

Automatic modulation recognition (AMR) is a challenging problem in intelligent communication systems and has wide application prospects. At present, although many AMR methods based on deep learning have been proposed, the methods proposed by these works cannot be directly applied to the actual wireless communication scenario, because there are usually two kinds of dilemmas when recognizing the real modulated signal, namely, long sequence and noise. This paper aims to effectively process in-phase quadrature (IQ) sequences of very long signals interfered by noise.

This paper proposes a general model for a modulation classifier based on a two-layer nested structure of long short-term memory (LSTM) networks, called a two-layer nested structure (TLN)-LSTM, which exploits the time sensitivity of LSTM and the ability of the nested network structure to extract more features, and can achieve effective processing of ultra-long signal IQ sequences collected from real wireless communication scenarios that are interfered by noise.

Experimental results show that our proposed model has higher recognition accuracy for five types of modulation signals, including amplitude modulation, frequency modulation, gaussian minimum shift keying, quadrature phase shift keying and differential quadrature phase shift keying, collected from real wireless communication scenarios. The overall classification accuracy of the proposed model for these signals can reach 73.11%, compared with 40.84% for the baseline model. Moreover, this model can also achieve high classification performance for analog signals with the same modulation method in the public data set HKDD_AMC36.

At present, although many AMR methods based on deep learning have been proposed, these works are based on the model’s classification results of various modulated signals in the AMR public data set to evaluate the signal recognition performance of the proposed method rather than collecting real modulated signals for identification in actual wireless communication scenarios. The methods proposed in these works cannot be directly applied to actual wireless communication scenarios. Therefore, this paper proposes a new AMR method, dedicated to the effective processing of the collected ultra-long signal IQ sequences that are interfered by noise.

The purpose of this paper is to design and construct an amplitude shift keying (ASK) modulator, which, using the digital binary modulating signal, controls a floating memristor emulator (MR) internally without the need for additional control circuits to achieve the ASK modulated wave.

A binary digital unipolar signal to be modulated is converted by a pre-processor circuit into a suitable bipolar modulating direct current (DC) signal for the control of the MR state, using current conveyors the carrier signal’s amplitude is varied with the change in the memristance of the floating MR. A high pass filter is then used to remove the DC control signal (modulating signal) leaving only the modulated carrier signal.

The results from the experiment and simulation are in agreement showed that the MR can be switched between two states and that a change in the carrier signals amplitude can be achieved by using an MR. Thus, showing that the circuit behavior is in line with the proposed theory and validating the said theory.

In this paper, the binary signal to be modulated is modified into a suitable control signal for the MR, thus the MR relies on the internal operation of the modulator circuit for the control of its memristance. An ASK modulation can then be achieved using a floating memristor without the need for additional circuits or signals to control its memristance.

Stability of a nonlinear, tuned amplifier has been investigated based on the describing function method. On stability, this paper means global asymptotic stability. The tuned amplifier comprises a saturated amplifying device with feedback and two resonators, at the input and the output. Describing function method here means introduction of the two-port describing functions.

Describing function method is applied, extended for two ports. Results from complex analysis and matrix algebra are heavily used. The two resonators have identical resonant frequency and bandwidth. Instability is represented by non-vanishing output perturbation for zero-input perturbation. Applying a simple transistor model with saturation and feedback, stability is analyzed in the form of output voltage as a function of input voltage.

Two-port scattering and admittance describing functions have been introduced. At a certain input voltage amplitude, instability appears in the form of unwanted sidebands, then at a higher input voltage, instability disappears, in good agreement with experiments. The hand calculated stability limits are in good agreement with the computer analysis.

The paper is based on an early publication of the author (Baranyi and Ladvánszky, 1984). Here, the full material is presented, explained step by step, extended and revised. All neglections that were earlier made in the author’s paper have been avoided here. This paper has significant tutorial value as well.

An overview of radio telemetry, concentrating on low power, short‐range systems which can be operated without equipment licences. Describes transmission mechanisms, aerials and the two main types of analogue modulation: amplitude modulation [AM] and frequency modulation [FM].Outlines the developments in radio data links and modulation schemes, the benefits of networks and the various methods of encoding data. Concludes that one of the biggest problems in radio telemetry is the different regulations across Europe making it virtually impossible to design a transmitter that is acceptable in more than one country. However, in Europe the situation is slowly changing, with new common standards for defining, evaluating and testing equipment coming into effect.

The purpose of this paper is to highlight the increasing use of rotary or angle encoders and examine two distinct types of non‐contact encoders that employ novel technologies to meet the demands of very different applications.

Firstly, examines the design characteristics of optical angle encoders which are used for precision applications such as rotary format computer‐to‐plate pre‐press machines, machine tool A, B and C axes, and surface mount machines. Then considers magnetic encoder design, including the latest OnAxis™ technology for lower cost applications which require less precision, but are often more physically demanding.

Different rotary motion applications demand different combinations of performance and features to optimise their function – some require accuracy, others repeatability, high‐resolution or low‐cyclic error for velocity loop control, plus cost can also be a key consideration.

There is an increasing need to control rotary motion. An appreciation of the design principles of optical angle and rotary magnetic encoders is necessary to ensure that the correct choice of encoder is made for each application. For an angle encoder system, trade‐offs should be made to determine a realistic specification, and whilst many factors can limit achievable accuracy, techniques are available for reducing any shortfall. For applications where cost constraints and lower accuracy specifications demand a magnetic encoder, robust OnAxis™ sensor technology is gaining acceptance amongst designers, and whilst many of the basic design principles of optical encoders still apply, other specific technical aspects, such as much lower resolution and accuracy must be understood before using these devices. Hidden design costs should also be understood such as installation timings and the environmental suitability of magnets.

Will aid designers of rotary motion systems to make a well‐informed selection of encoder type, based on the detailed needs of their applications, including accuracy and cost budgets.

Wireless sensor networks (WSN), as a solution for buried water pipe monitoring, face a new set of challenges compared to traditional application for above-ground infrastructure monitoring. One of the main challenges for underground WSN deployment is the limited range (less than 3 m) at which reliable wireless underground communication can be achieved using radio signal propagation through the soil. To overcome this challenge, the purpose of this paper is to investigate a new approach for wireless underground communication using acoustic signal propagation along a buried water pipe.

An acoustic communication system was developed based on the requirements of low cost (tens of pounds at most), low power supply capacity (in the order of 1 W-h) and miniature (centimetre scale) size for a wireless communication node. The developed system was further tested along a buried steel pipe in poorly graded SAND and a buried medium density polyethylene (MDPE) pipe in well graded SAND.

With predicted acoustic attenuation of 1.3 dB/m and 2.1 dB/m along the buried steel and MDPE pipes, respectively, reliable acoustic communication is possible up to 17 m for the buried steel pipe and 11 m for the buried MDPE pipe.

Although an important first step, more research is needed to validate the acoustic communication system along a wider water distribution pipe network.

This paper shows the possibility of achieving reliable wireless underground communication along a buried water pipe (especially non-metallic material ones) using low-frequency acoustic propagation along the pipe wall.

This article provides a broad overview of telecommunications and network‐related technologies. Topics covered include identification and review of network elements, analog and digital signals, synchronous and asynchronous transmission formats, transmission media and equipment, transmission techniques and characteristics, multiplexing, network types, access technologies, network architectures and topologies, local‐area network technologies and attributes, protocols and protocol issues, gateways, internetworking, local networking alternatives, equipment certification, and various aspects of network management. It is intended to provide the practicing professional in the field of library and information science with a broad, up‐to‐date technical review that might serve to support and facilitate further investigation of current developments in networks and networking. Although the broad range of topics is not treated in depth, numerous references are provided for further investigation.

The purpose of this paper is to introduce a new linearization technique known as the passive linearizer technique which does not affect the power added efficiency (PAE) while maintaining a power gain of more than 20 dB for complementary metal oxide semiconductor (CMOS) power amplifier (PA).

The linearization mechanism is executed with an aid of a passive linearizer implemented at the gate of the main amplifier to minimize the effect of C_gs capacitance through the generation of opposite phase response at the main amplifier. The inductor-less output matching network presents an almost lossless output matching network which contributes to high gain, PAE and output power. The linearity performance is improved without the penalty of power consumption, power gain and stability.

With this topology, the PA delivers more than 20 dB gain for the Bluetooth Low Energy (BLE) Band from 2.4 GHz to 2.5 GHz with a supply headroom of 1.8 V. At the center frequency of 2.45 GHz, the PA exhibits a gain of 23.3 dB with corresponding peak PAE of 40.11% at a maximum output power of 14.3 dBm. At a maximum linear output power of 12.7 dBm, a PAE of 37.3% has been achieved with a peak third order intermodulation product of 28.04 dBm with a power consumption of 50.58 mW. This corresponds to ACLR of – 20 dBc, thus qualifying the PA to operate for BLE operation.

The proposed technique is able to boost up the efficiency and output power, as well as linearize the PA closer to 1 dB compression point. This reduces the trade-off between linear output power and PAE in CMOS PA design.

The proposed CMOS PA can be integrated comfortably to a BLE transmitter, allowing it to reduce the transceiver’s overall power consumption.

Feature extraction is a key issue to machine condition monitoring and fault diagnosis. The features must contain the necessary discriminative information for the fault classifier to have any chance of accurate classification. This paper presents a study that uses principal component analysis to reduce dimensionality of the feature space and to get an optimal subspace for machine fault classification. Industrial gearbox vibration signals measured from different operating conditions are analyzed using the above method. The experimental results indicate that the method extracts diagnostic information effectively for gear fault classification and has a good potential for application in practice.