Ultra low-cost membrane technology for millimeterwave applications

With the rapid development of smart grids, on-line monitoring systems of transmission and distribution lines are more necessary than ever before.However, it is a difficult problem to supply the power for the on-line monitoring devices.Wireless power transfer (WPT) is a promising technology for many potential applications [1-3], such as wireless sensors [4], space solar-power stations (SSPSs) [5], implantable medical devices (IMDs) [6], unmanned aerial vehicles (UAVs) [7] and RF energy harvesting (EH) [8].Thus, WPT technology is regard as an efficient method to realize power supply for devices in special environment, such as high-voltage environment.The popular WPT techniques include: magnetic-field coupled wireless power transfer (MC-WPT), electric-filed coupled wireless power transfer (EC-WPT), microwave power transmission (MPT), laser power transfer (LPT) and ultrasonic power transmission (UPT).In this paper, by employing MC-WPT and MPT technologies, the power transmission from high-tension lines to on-line monitoring devices is achieved.Moreover, as a key part of the WPT system, a 5.8GHz microwave rectifier with wide power range and high efficiency is proposed based on the nonlinear characteristics of diode wideband impedance matching method.The proposed rectifier consists of two sub circuits, operating at the high power region and the low power region, respectively.The transmission line in series with the diode has the effect of compensating the imaginary part of the diode impedance and suppressing higher harmonics, and the 4 transmission line is used to reverse the change of the diode impedance relative to the input power.From the rectification efficiency curve of the rectifier, it can be seen that the reflection coefficient is below -10 dB from 0 dBm to -30 dB.The rectification efficiency of the rectifier is 70% at the frequency of 5.8 GHz and the input power of 12.9 dBm, and the rectification efficiency is more than 60% from -0.5 dBm to 26 dBm.The proposed rectifier circuit has advantages of large power range, high efficiency, compact circuit size and low-cost.

Natural gas is one of the most highly used resources, not only as a fuel but also as a raw material for many industrial processes. In addition, it is an environmental friendly fuel due to its lower greenhouse gas emission than that of coal or oil. However, it is a nonrenewable energy source and the quality of the available resources is expected to deplete continuously. In this scenario, membrane technologies can play an important role in the purification of the reduced and contaminated resources, competing with the current technologies owing to their simpler adaptability to different feed compositions, lower energy consumption and investment costs. In this review, the current state of the natural gas sources, including nonconventional resources (tight/shale gas and biogas), is explored, along with the current market status of the conventional natural gas. A comparison between the conventional purification technologies and membrane processes is provided, together with the currently available commercial membranes as well as new materials. Furthermore, the latest materials in research stage are reviewed, pointing out their limitations to the current membranes technologies. Finally, future research trends to overcome the current membrane technology limitations are proposed, and the conclusions are addressed.

VOC recovery with membrane technology

Membrane process optimization for carbon capture

Piezoelectricity induced by pulsed hydraulic pressure enables in situ membrane demulsification and oil/water separation

Membrane desalination and water re-use for agriculture: State of the art and future outlook

Innovative membrane processes are considered a very important segment of controllable separation processes, such as water treatment, gas separation and organic purification. One of the challenges in membrane technology is the challenge of selecting and fabricating membrane material for excellent selectivity and good permeability for selected particle sizes. The utmost operational challenge perturbing the performance of membrane technology is membrane fouling which occur as a result of insoluble materials covering the membrane surface, leading to a reduction in water quality. Other factors perturbing the performance of membrane technology are energy usage and greenhouse emission. Furthermore, the necessity to react to climate change is another major challenge for membrane technology. An excellent membrane should have high stiffness in order to withstand high pressures applied, large surface area and micro- or nanopore structures for excellent selectivity and good permeability for selected particle sizes. The transport of ions and fluid at molecular level, controlled at the nanometer-scale using membranes provide substantial capacity for high selectivity and high fluxes. The potential applications of nanoporous membranes are strongly subjected to the chemical and physical properties of a membrane material. The effective pores size, porosity, uniformity, thickness, surface chemistry and morphology also have influence on membrane separation performance. We reviewed the fabrication and potential applications of nanoporous membranes for separation processes, operational challenge, energy usage, greenhouse emission and effect of climate change. Thus, the major points, include: (1) fabrication methods of nanoporous membranes for excellent selectivity and good permeability for selected particle sizes, (2) Theoretical modeling and simulations of nanoporous membranes, (3) potential applications of nanoporous membranes, (4) the recent discovery of novel nanoporous membrane structures aimed at overcoming the challenge of fouling, (5) the challenge of energy usage, (6) addressing climate change as a contributing factor to the challenges of water treatment industry and membrane technology.

A novel periodic substrate integrated waveguide (SIW) leaky-wave structure using TE20 mode transmission line (TL) for millimeter-wave antenna applications is proposed and studied in this paper. The electric field distribution and dispersion properties for TE20 mode SIW - TL is first studied and presented. Based on the current distribution of the TE20 mode, elliptical slots are periodically embedded on the surface of the SIW-TL, which not only achieves backward to forward continuous beam-steered boresight radiation, but also maintains good TE20 mode transmission. Two half-wavelength slots are etched on the bottom of SIW, which successfully excite TE20 mode in TL. For experimental verification, a periodic TE20 mode SIW-TL leaky-wave antenna is fabricated. The measured and simulated results are in good agreement. The measured -10 dB bandwidth, peak gain, beam scanning range is 25.5-33.8 GHz (28.0 %), 15.4 dBi and 50° to -18° (backward to forward), respectively. It demonstrates a simple structure and good travelling wave properties with wide bandwidth, high gain, and good radiation performance, which is suitable for 5G millimeterwave application.

Organic nonvolatile memory has been considered a low-cost memory technology for flexible electronics and Internet-of-things (IoT). However, a major concern is the nonuniformity of memory units, which is primarily caused by random grain boundaries, interface defects, and charge traps, making it difficult to develop high-density reliable memory arrays. This nonuniformity problem would induce read error, which is directly caused by the narrow distribution margin of memory states and low noise tolerance in conventional organic memory cells. To break this limitation, a novel 2T memory cell employing a NOT-gate-like architecture achieving self-enhancing noise tolerance is presented. This unique cell consists of a pair of commonly-gated memory transistors with contradictory "write-and-erase" features. It functions as a voltage divider, producing a well-distinguished binary voltage output capability. The concept and design model of this brand-new 2T memory cell is thoroughly discussed. It is originally characterized by noise-tolerant memory cells irrespective of device nonuniformity. The noise tolerance range of this 2T memory cell is also investigated. The binary voltage-readable memory state with a large noise tolerance range is obtained. Moreover, the conceptual design of the 1T2T FeRAM cell is further developed for low-cost voltage-readable memory technology in wearable electronic applications.

The critical need for higher power efficiency and bandwidth transceiver design has significantly increased as mobile devices, such as smart phones, laptops, tablets, and ultra-portable personal digital assistants continue to be constructed using heterogeneous intellectual properties such as central processing units (CPUs), graphics processing units (GPUs), digital signal processors, dynamic random-access memories (DRAMs), sensors, and graphics/image processing units and to have enhanced graphic computing and video processing capabilities. However, the current mobile interface technologies which support CPU to memory communication (e.g. baseband-only signaling) have critical limitations, particularly super-linear energy consumption, limited bandwidth, and non-reconfigurable data access. As a consequence, there is a critical need to improve both energy efficiency and bandwidth for future mobile devices.;The primary goal of this study is to design an energy-efficient reconfigurable mobile memory interface for mobile computing systems in order to dramatically enhance the circuit and system bandwidth and power efficiency. The proposed energy efficient mobile memory interface which utilizes an advanced base-band (BB) signaling and a RF-band signaling is capable of simultaneous bi-directional communication and reconfigurable data access. It also increases power efficiency and bandwidth between mobile CPUs and memory subsystems on a single-ended shared transmission line. Moreover, due to multiple data communication on a single-ended shared transmission line, the number of transmission lines between mobile CPU and memories is considerably reduced, resulting in significant technological innovations, (e.g. more compact devices and low cost packaging to mobile communication interface) and establishing the principles and feasibility of technologies for future mobile system applications. The operation and performance of the proposed transceiver are analyzed and its circuit implementation is discussed in details. A chip prototype of the transceiver was implemented in a 65nm CMOS process technology. In the measurement, the transceiver exhibits higher aggregate data throughput and better energy efficiency compared to prior works.

Introduction SiGe BiCMOS technology is an excellent choice for RF (radio frequency) and mm-wave applications as it combines the best features of CMOS logic, high-performance SiGe heterojunction bipolar transistors (SiGe HBTs), and RF passives like transmission lines, capacitors, inductors, Schottky barrier diodes (SBDs), p-i-n diodes, and resistors. RF models for all of these devices and process design kits are readily available for the design and simulation of RF circuits. In addition, BiCMOS technologies generally support multiple HBTs having different breakdown voltage, noise, and performance specifications for varied applications. The selection of any technology for mm-wave applications like power amplifiers (PAs) or transmitters is dependent not only on the performance of the technology but more so on the economics and total cost of the project integration. Compound semiconductor HBTs like InP and GaAs have better cut-off frequencies and breakdown voltage but lose to silicon technologies in terms of cost and integration. RFCMOS technologies may have similar performance specifications to the SiGe HBTs but BiCMOS is still preferred over RFCMOS for several reasons. At the same lithography node, SiGe HBT has superior performance and breakdown voltage to the CMOS devices. For equal performance CMOS requires much more aggressive lithography (> n + 2 gen) and as such is significantly more expensive than SiGe BiCMOS. SiGe HBTs have a higher breakdown voltage and power handling capability, higher operating voltage, higher self-gain, better voltage swing, better impedance matching, and better linearity than CMOS. This chapter will explore these and other aspects of the SiGe BiCMOS technology that make it ideal for silicon mm-wave applications like power amplifiers and transmitters. The chapter begins with a basic graded-base SiGe HBT device physics description followed by a discussion about the processing technology used to fabricate the device emphasizing aspects that impact high-performance mm-wave SiGe HBTs. A detailed comparison of performance trends across various technologies and industries is presented next. For mm-wave circuits there is an additional set of metrics such as breakdown voltage, noise figure, linearity, and thermal effects which are key to mm-wave applications. Several sections are devoted to discussion of breakdown voltage, thermal effects, and noise figure. In addition to the SiGe HBT transistors, silicon RF passives are also important and there is a discussion on Schottky diodes, PIN diodes, and other passives readily available in BiCMOS technologies.

Transmission lines and filter networks: by John J. Karakash. 413 pages, diagrams, 16 × 24 cm. New York, Macmillan Co., 1950. Price, $6.00

The biological inner ear, or cochlea, is a sophisticated signal processing system that performs spectrum analysis over an ultra-broadband frequency range of ~20 Hz to 20 kHz with exquisite sensitivity and high energy efficiency. Electronic cochlear models, which mimic the exponentially-tapered structure of the biological inner ear using transmission lines or filter cascades, have been shown to be fast and extremely efficient spectrum analyzers at both audio and radio frequencies. We have previously used this model to create single-chip RF spectrum analyzers, and have recently developed improved output encoding methods for such cochlea-like analyzers. A prototype analyzer has been designed in the UMC 65 nm RF-CMOS process. It includes a bidirectional cochlea model with 50 parallel exponentially-spaced output stages and analyzes the radio spectrum from 0.8-8.3 GHz. The outputs are encoded as delta-sigma (ΔΣ) modulated digital signals that are demodulated and analyzed in real-time by a digital back-end implemented on a field-programmable gate array (FPGA). The resulting system is expected to be useful as a broadband spectrum sensor in cognitive radio networks.

V On Basic Analogies and Principal Differences Between Optical and Electronic Information

Membrane technology has emerged as an effective solution for the purification of oily wastewater, particularly in the separation of oil-in-water (O/W) emulsions. However, challenges, such as membrane fouling and the development of robust ceramic membranes with superior stability, continue to limit their widespread application. In this work, helical carbon nanotubes (HCNTs) with interlocking structures were grown in ceramic support channels through the airflow-induced chemical vapor deposition (CVD) method to fabricate membrane material with high hydrophilicity and underwater oleophobicity. The influence of CVD parameters on the growth of HCNTs and the membrane separation performance for O/W emulsions were studied systematically. The optimal HCNTs-SiC composite membrane was prepared at 600 °C, featuring a pore size of 0.95 μm and flux of 229.29 L·m-2·h-1. This membrane demonstrated exceptional purification efficiency (99.99%) for a 500 ppm O/W emulsion, along with a stable flux of 32.48 L·m-2·h-1 under a transmembrane pressure (TMP) of 1.5 bar. Furthermore, the unique membrane structure and surface heterogeneity contributed to its long service life and excellent recovery capability. This work provides a novel strategy for designing high-performance ceramic membranes for oil-water separation, offering potential solutions to current limitations in membrane technology.