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Additive manufacturing (AM) of thermoplastic polymers for powder bed fusion processes typically requires each layer to be fused before the next can be deposited. The purpose of this paper is to present a volumetric AM method in the form of deeply penetrating radio frequency (RF) radiation to improve the speed of the process and the mechanical properties of the polymer parts.

The focus of this study was to demonstrate the volumetric fusion of composite mixtures containing polyamide (nylon) 12 and graphite powders using RF radiation as the sole energy source to establish the feasibility of a volumetric AM process for thermoplastic polymers. Impedance spectroscopy was used to measure the dielectric properties of the mixtures as a function of increasing graphite content and identify the percolation limit. The mixtures were then tested in a parallel plate electrode chamber connected to an RF generator to measure the heating effectiveness of different graphite concentrations. During the experiments, the surface temperature of the doped mixtures was monitored.

Nylon 12 mixtures containing between 10% and 60% graphite by weight were created, and the loss tangent reached a maximum of 35%. Selective RF heating was shown through the formation of fused composite parts within the powder beds.

The feasibility of a novel volumetric AM process for thermoplastic polymers was demonstrated in this study, in which RF radiation was used to achieve fusion in graphite-doped nylon powders.

The purpose of this paper is to investigate the possibility to replace radio equipment compliance requirements based on equipment parameters with a set of simple metrics that accurately reflects spectrum utilization and spectrum-sharing efficiency.

The approach taken is to go back to the basic factors that determine radio system behavior in a shared spectrum environment: radio frequency power, duty cycle and frequency occupation. By normalizing these parameters, device specificity is avoided and a statistical perspective on spectrum utilization and sharing becomes possible.

The analysis shows that two technology-neutral metrics would be adequate to govern spectrum utilization and sharing: a spectrum utilization metric and a spectrum-sharing efficiency metric. These metrics form the core of regulatory requirements for shared frequency bands. Each shared frequency band could be assigned criteria based on these metrics that take into account the types of applications for which that band will be used.

This work is a first step that identifies the main factors that affect shared spectrum usage from a statistical point of view. More work is needed on the relationship between real-world interference and its abstraction in the spectrum-sharing rules.

The metrics proposed could be considered as the basis for a new approach to the regulation of the license-exempt spectrum, and, by extension, as the basis for generic compliance criteria. Their use would facilitate the compliance assessment of software-defined radio technology.

This work has no direct social implications.

This paper combines new work on spectrum utilization criteria with extensions of previous work on spectrum-sharing efficiency into a comprehensive proposal for a new approach to the regulation of the license-exempt spectrum.

To provide practitioners of management a sense of the importance of strategically leveraging the current and historic development of radio frequency identification (RFID) in order to find inexpensive applications of radio frequency‐based (RF) technologies in many areas.

A review of the applied literature on RFID, as well as from practical experience, resulted in a basic model of viewpoint to understand the nature of the emergent RF‐based industry.

Wal‐Mart and other cost sensitive and value chain progressive companies' usage of RFID‐based technology should revolutionize the method that companies' track inventory. However, some of the disadvantages include costs, training, product label and supplies, and privacy infringement. One asset to companies like Wal‐Mart is pallet tracking because it improves on‐time inventory delivery. This helps Wal‐Mart since they rely on just‐in‐time ordering.

RFID is currently used in many industries such as transportation and distribution, manufacturing and processing, and security and law enforcement. The advantages RFID gives to companies are the following: enhanced record management, customer behavior patterns, and accurate inventory tracking.

This paper describes RFID and its implementation process in an academic manner, some disadvantages of RFID, and examples of how the technology can improve customer relationship management (CRM) are discussed. Originality/value – This form of identification can be used in large stores like Wal‐Mart to receive real time information. By implementing RFID, companies will create a fully integrated supply chain system. Traditionally, many supply chain management (SCM) research has simply viewed RF‐based technology as a technological innovation, not a transformational event as this paper presents.

The aim of this study was to prove that radio-frequency (RF) energy with 13.56 MHz can be used for heating building structures in a controlled manner exploiting the advantage that homogeneous heating with sufficient penetration depths can be achieved.

Because parallel electrodes on both sides of the heated structure cannot be used in many practical applications, two special electrode designs have been developed by modeling the field distribution and energy absorption and by carrying out test experiments to validate the simulation results.

One solution is based on a two-dimensional surface capacitor providing certain penetration depths and being especially suitable for treating thin structures such as wooden parquet floor. Such an arrangement can be particularly used for pest control even when sensitive surfaces have to be protected. The other solution uses a capacitive coupling between the grounded shielding and an electrode or an equivalent structure (e.g. moist soil) at the other side of the masonry to establish a sufficiently strong electrical field between a “hot” electrode on the side of the shielding and the coupled rear electrode.

Both solutions significantly enhance the application potential of RF heating.

Recent work has demonstrated the possibility of selectively sintering polymer powders with radio frequency (RF) radiation as a means of rapid, volumetric additive manufacturing. Although RF radiation can be used as a volumetric energy source, non-uniform heating resulting from the sample geometry and electrode configuration can lead to adverse effects in RF-treated samples. This paper aims to address these heating uniformity issues by implementing a computational design strategy for doped polymer powder beds to improve the RF heating uniformity.

Two approaches for improving the RF heating uniformity are presented with the goal of developing an RF-assisted additive manufacturing process. Both techniques use COMSOL Multiphysics® to predict the temperature rise during simulated RF exposure for different geometries. The effectiveness of each approach is evaluated by calculating the uniformity index, which provides an objective metric for comparing the heating uniformity between simulations. The first method implements an iterative heuristic tuning strategy to functionally grade the electrical conductivity within the sample. The second method involves reorienting the electrodes during the heating stage such that the electric field is applied in two directions.

Both approaches are shown to improve the heating uniformity and predicted part geometry for several test cases when applied independently. However, the greatest improvement in heating uniformity is demonstrated by combining the approaches and using multiple electrode orientations while functionally grading the samples.

This work presents an innovative approach for overcoming RF heating uniformity issues to improve the resulting part geometry in an RF-assisted, volumetric additive manufacturing method.

The purpose of the paper is to present a frequency-changing technique to realize a fast start-up radio frequency (RF) energy harvester.

First, a simple analysis of the input impedance of the rectifier circuit is presented, and based on the analysis, it is shown how the input impedance of the rectifier is changed during the rectifier charging. Then, the frequency-changing technique is presented in which the variation of the rectifier input reactance (capacitance) is partly compensated by changing the frequency of the transmitted RF signal. A harvester consisting of a four-stage rectifier and a simple series matching inductor, implemented based on Schottky diode, is employed to verify the technique.

With the input available power of −12 dBm, the simulated and the measured results prove that the proposed frequency-changing method compared to the typical fixed-frequency method shows more than 30 per cent decrease in the transient time to reach 0.5 V output voltage, while the final harvested output voltage is unchanged.

A frequency-changing technique is presented.

Provide information on the effects of flux residues from surface mount assembly on radio frequency (RF) performance.

A series of test vehicles designed to evaluate the RF performance on various test patterns and some simple circuits. Empirical testing is used in determining the data.

Provides a methodology for checking the performance of flux residues as well as information on the performance of a few different flux residue types.

This is not an all encompassing project and the results may not extrapolate out to higher frequency ranges.

A good source of reference that can be used to understand the impacts of the assembly process on RF performance.

This paper shows the effect of assembly materials (flux residues) on a real circuit and not just test patterns. It can give a basic understanding to process engineers of the potential impact of the assembly process on a RF circuit.

The purpose of this paper is to present a new class of printed circuit board (PCB)‐based, radio frequency micro‐electro‐mechanical systems (RF‐MEMS) switches and to describe the packaging method and evaluate performance.

Traditional PCB materials and processes were combined with photolithographic high‐density interconnect (HDI) and MEMS to form 3D high‐performance RF switches.

A new type of MEMS RF switch has been developed on a PCB platform. Using processes analogous to those used for silicon MEMS, PCB, and HDI technologies were utilized to fabricate these 3D structures. The PCB‐based microstructures are “mil‐scale” rather than the “micro‐scale” of silicon MEMs. A co‐fabrication packaging method for the MEMS RF switch was also developed. The PCB‐based MEMS switches have demonstrated excellent RF performance and “hot‐switching” RF power‐handling capability. PCB‐based MEMS RF switches have the advantages of low cost and amenability to scale‐up for a high degree of integration.

Further development on photo imageable dielectric materials will enable this technology to improve yield and processability.

The paper describes the development of PCB‐based MEMS RF switches. These elements will enable new applications and enhance the functionality of PCBs. They are also more amenable to system integration compared with silicon MEMS.

The purpose of this paper is to present the results of an analytical and experimental research for the development of an innovative product designated RFID environment (RFID‐Env). This software is designed for the use of professionals in computer systems and plant engineering who are engaged in research and development (R&D) of ultra high frequency (UHF) passive radio frequency identification (RFID) systems as applied to the management and operation of logistic supply chains.

The RFID‐Env makes it possible to simulate on computer screens a complete RFID‐Env by processing user data on the technical and physical characteristics of real or virtual RFID‐Envs. Information outputted can include descriptions of the performance to be expected from a given configuration and detailed reports as to whether that particular configuration will succeed in reading all the RFID tags flowing through a defined system.

The paper shows the models and methods on how these simulations can be performed, and this is the major scientific contribution of this work, i.e. what are the logical and physical models that enable the development of software simulators for RFID‐Envs.

This work will be continued to introduce more consideration of the physical environment, such as the interferences produced by the tagged products themselves by scattering the radio frequency (RF) signals, and the models, positioning and focusing of the antennas. New RF prediction models shall be created along the continuation of this paper, with the purpose to rise the amount of environments that can be simulated.

The product is intended for use by developers in computer sciences, and by engineers doing R&D for the solution of RFID problems, and makes it possible to simulate a complete range of virtual RFID‐Envs so that R&D can proceed in a non‐factory atmosphere.

There are only a few related papers that consider in an isolated form some of the problems approached here, but it was not found models that proposed as an integrated form all the processing to an RFID‐Env simulation like here presented.

The purpose of this paper is to present the high-frequency performance of 0.13-μm n-type metal-oxide-semiconductor (NMOS) transistors with various multi-finger configurations for implementation in millimeter-wave (mm-wave) frequency.

A folded-like double-gate transistor layout is designed to enable the transistor to work in the mm-wave region. Different sizes of transistors with variation in finger width (W_F ) and number of fingers (N_F ) were fabricated to determine the optimum size of the transistor. The extrinsic parasitic elements of selected transistors were extracted and investigated. The radio frequency (RF) performance of these samples were then analyzed and compared.

The proposed layout performed well with the highest maximum oscillation frequency (f_max ) achieved at 122 GHz. Based on the comparison done, the optimum W_F obtained for the layout is at 2.0 μm. It is found that the extrinsic parasitic capacitance is more dominant than the parasitic resistance in affecting the f_max . In s-parameter analysis, it is observed that the transistor with the least N_F has smaller variance in small-signal gain throughout the measurement frequency. The maximum stable gain for the samples is also found to be roughly similar and independent of N_F .

A new layout structure for an NMOS transistor that works in mm-wave frequency is proposed. Experimental analyses presented here cover for both N_F and W_F , unlike others which focus on either N_F or W_F only.