Backscatter radio - wireless communication by modulating signals scattered from a transponder (RF tag) is fundamentally different conventional because it involves two distinct links: the power-up link for powering passive RF tags, and backscatter describing communication. Because of severe power constraints on tag, thorough knowledge channel necessary to maximize backscatter-radio radio-frequency identification (RFID) system performance. This article presents four budgets that account major...

Backscatter radio systems, including high frequency identification (RFID), operate in the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dyadic backscatter channel</i> - a two-way pinhole channel that has deeper small-scale fades than of conventional one-way channel. This paper shows xmlns:xlink="http://www.w3.org/1999/xlink">pinhole diversity</i> is available rich scattering environment caused by modulating with multiple RF tag antennas no...

The concept of security regions is used to systematically and objectively compare the impact various FACTS devices on behaviour power systems. Scalar measures steady-state performance a system with are quantify this impact. Such obtained by solving an optimal flow within constraints region. ideal device introduced as means establish theoretical upper bound any realizable FACTS. tested compared against nonideal including variable series reactance phase-shifter. Simulations IEEE 118 30 bus...

Passive radio frequency (RF) tags in the UHF and microwave bands have drawn considerable attention because of their great potential for use many identification (RFID) applications. However, more basic research is needed to increase range reliability a passive RF tag's link, particularly when tag placed onto any lossy dielectric or metallic surface. This paper presents two new useful forms link budget that describe power an system attached object. These budgets are dependent upon gain...

A major limitation in passive radio frequency identification (RFID) is the read range from reader to tag, which limited by power available integrated circuit (RFIC). The power-optimized waveform (POW) a new type of multiple-tone carrier and modulation scheme that designed improve efficiency charge pump-based RFICs. This paper presents POW concept, an estimation effects on existing class 1 generation 2 RFID systems, several example POWs, simulation results, measurement results gains using POW.

Soybean cyst nematode (SCN) is the most destructive soybean pest worldwide. Host plant resistance environmentally friendly and cost-effective way of mitigating SCN damage to soybeans. However, overuse resistant (Glycine max (L.) Merr.) cultivars from limited genetic resources has resulted in race shifts many soybean-growing areas. Thus, exploration novel sources dissection basis are urgently needed. In this study, we screened 235 wild soja Sieb. & Zucc.) accessions identify genotypes HG Type...

Optimization for complex systems in engineering often involves the use of expensive computer simulation. By combining statistical emulation using treed Gaussian processes with pattern search optimization, we are able to perform robust local optimization more efficiently and effectively than when either method alone. Our approach is based on augmentation patterns location sets generated through improvement prediction over input space. We further develop a computational framework asynchronous...

Short-distance, millimeter-level ranging based on backscatter RF tags remains a challenge today. We propose composite dual-frequency continuous-wave and (DFCW/CW) radar system for localization of tags. The coarse DFCW range result is used to correct the cycle ambiguity more accurate CW result. A minimum mean square error (MMSE)-based method employed combine data, given spectrum constraints. concept demonstrated with custom 5.8-GHz tag in typical indoor laboratory environment strong...

High-frequency backscatter radio systems operate in the dyadic channel, a pinhole channel whose envelope probability density function and bit-error-rate performance are strongly affected by link correlation - between forward links of channel. This paper shows that is most detrimental for using co-located reader transmitter receiver antennas single RF transponder antenna. It shown separate multiple will decrease effects near maximum can be achieved with less than 0.6.

Multipath fading can be heavy for ultra-high frequency (UHF) and microwave backscatter radio systems used in applications such as identification (RFID). This paper presents measurements of on the modulated signal backscattered from a transponder that use multiple antennas at interrogator transponder. Measurements were performed 5.8 GHz estimates channel envelope distributions fade margins calculated. Results show multipath reduced using antennas, bistatic interrogators with widely separated...

We describe an asynchronous parallel derivative-free algorithm for linearly constrained optimization. Generating set search (GSS) is the basis of our method. At each iteration, a GSS computes directions and corresponding trial points then evaluates objective function value at point. Asynchronous versions have been developed in unconstrained bound-constrained cases which allow iterations to continue (and new be generated evaluated) as soon any other point completes. This enables better...

Iterative methods are proposed for certain augmented systems of linear equations that arise in interior general nonlinear optimization. Interior define a sequence KKT represent the symmetrized (but indefinite) associated with Newton's method point satisfying perturbed optimality conditions. These involve both primal and dual variables become increasingly ill-conditioned as optimization proceeds. In this context, an iterative solver must not only handle ill-conditioning but also detect...

We consider methods for large-scale unconstrained minimization based on finding an approximate minimizer of a quadratic function subject to two-norm trust-region inequality constraint. The Steihaug–Toint method uses the conjugate-gradient algorithm minimize over sequence expanding subspaces until iterates either converge interior point or cross constraint boundary. benefit this approach is that solution may be obtained with minimal work and storage. However, does not allow accuracy...

UHF and microwave backscatter RF-tag systems, including radio frequency identification (RFID) sensor experience multipath fading that can be more severe than found in a conventional transmitter-to-receiver channel. Previous work has shown reduced on the modulated-backscatter signal received from RF tag non-line-of-sight (NLOS) channel if one antenna is used to modulate backscatter. This paper presents first measurements for tags using multiple antennas at 5.79 GHz - center of 5.725-5.850...

Measurements of the magnetoquasistatic fields generated from a magnetic dipole (an electrically small current loop) located above Earth are presented and compared to calculations using complex image theory. With horizontal (i.e., surface normal parallel Earth) emitting loop at height <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h</i> copolarized receiving xmlns:xlink="http://www.w3.org/1999/xlink">z</i> ≥ 0, coupling between dipoles was...

Traditional wireless position-location systems, operating using propagating waves, suffer reduced performance in non-line-of-sight (NLoS) applications. systems that use quasistatic fields have instead been limited to short ranges, progressive direction-finding applications, require RF fingerprinting, or do not provide complete immunity dielectric obstacles (use of electric fields). These limitations impose severe restrictions applications such as tracking an American football during game...

Machine learning applications often require hyperparameter tuning. The hyperparameters usually drive both the efficiency of model training process and resulting quality. For tuning, machine algorithms are complex black-boxes. This creates a class challenging optimization problems, whose objective functions tend to be nonsmooth, discontinuous, unpredictably varying in computational expense, include continuous, categorical, and/or integer variables. Further, function evaluations can fail for...

This paper presents measured antenna impedance and patterns of a horizontally oriented folded dipole as it is moved toward metal ground plane. The 915 MHz measurements on different antennas provide rules-of-thumb for RFID link design suggest that changing thicknesses may make tags more resistant to on-object degradations

Many optimization problems are characterized by expensive objective and/or constraint function evaluations paired with a lack of derivative information. Direct search methods such as generating set (GSS) well understood and efficient for derivative-free unconstrained linearly constrained problems. This paper presents study heuristic algorithms that address the more difficult problem general nonlinear constraints where derivatives or functions unavailable. We focus on penalty use GSS to solve...

A novel approach for pairing RFID-enabled devices is introduced and evaluated in this work. Two or more are moved simultaneously through the radio field close proximity of one RFID readers. Gesture recognition applied to identify movements devices, mark them as a pair. This application interest social networks game applications which play patterns with toys used establish virtual friendships. In wireless networking, it can be user-friendly association devices. The here works off-the-shelf...

Machine learning (ML) problems are often posed as highly nonlinear and nonconvex unconstrained optimization problems. Methods for solving ML based on stochastic gradient descent easily scaled very large but may involve fine-tuning many hyper-parameters. Quasi-Newton approaches the limited-memory Broyden-Fletcher-Goldfarb-Shanno (BFGS) update typically do not require manually tuning hyper-parameters suffer from approximating a potentially indefinite Hessian with positive-definite matrix....

Using new, analytic expressions for the envelope probability density function (PDF) of M times L N dyadic backscatter channel, this paper demonstrates that modulating using multiple RF tag antennas can reduce small-scale fading. Several practical design guidelines are presented to exploit property channel and increase range reliability without a change in signaling scheme.