Small Output Research Articles

Efficient dose-rate correction of silicon diode relative dose measurements.

Silicon diodes are often the detector of choice for relative dose measurements, particularly in the context of radiotherapy involving small photon beams. However, a major drawback lies in their dose-rate dependency. Although ionization chambers are often too large for small field output factor (OF) measurements, they are valuable instruments to provide reliable percent-depth dose (PDD) curves in reference beams. The aim of this work is to propose a practical and accurate method for the characterization of silicon diode dose-rate dependence correction factors using ionization chamber measurements as a reference. The robustness of ionization chambers for PDD measurements is used to quantify the dose-rate dependency of a diode detector. A mathematical formalism, which exploits the error induced in percent-depth ionization (PDI) curves for diodes by their dose-rate dependency, is developed to derive a dose-rate correction factor applicable to diode relative measurements. The method is based on the definition of the recombination correction factor given in the addendum to TG 51 and is applied to experimental measurements performed on a CyberKnife M6 radiotherapy unit using a PTW 60012 diode detector. A measurement-based validation is provided by comparing corrected PDI curves to measurements performed with a PTW 60019 diamond detector, which does not exhibit dose-rate dependence. Results of dose-rate correction factors for PDI curves, off-axis ratios (OARs), tissue-phantom ratios, and small field OFs are coherent with the expected behavior of silicon diode detectors. For all considered setups and field sizes, the maximum correction and the maximum impact of the uncertainties induced by the correction are obtained for OARs for the 60 mm collimator, with a correction of 2.5% and an uncertainty of 0.34%. For OFs, corrections range from 0.33% to 0.82% for all field sizes considered, and increase with the reduction of the field size. Comparison of PDI curves corrected for dose-rate and for in-depth beam quality variations illustrates excellent agreement with measurements performed using the diamond detector. The proposed method allows the efficient and precise correction of the dose-rate dependence of silicon diode detectors in the context of clinical relative dosimetry.

Assessment of Addition-Chain-Based Masked S-Box Using Deep-Learning-Based Side-Channel Attacks

Masking schemes are considered to be effective countermeasures to protect Internet-of-Things devices from side-channel attacks. Deep-learning-based side-channel attacks (DL-SCAs) have been demonstrated to be very effective targeting on masked implementations. In this paper, we investigate the resistance of a popular computation-based masking scheme against DL-SCAs, that is, the addition-chain-based one. We find that addition chain introduces computations of intermediate monomials over F 2 n with smaller output sizes, which decreases its resistance against DL-SCAs. Specifically, we first use mutual information metric to evaluate the side-channel resistance of different monomials from an information theory point of view. Next, we further propose the Kullback–Leibler divergence ratio as an evaluation metric to analyze the impact of monomial output size on DL-SCAs. The measurement values show that the monomial with smaller output size is less-resistant against DL-SCAs. Then we conduct simulated and practical experiments respectively to verify it. In simulated experiments, we perform DL-SCAs on first-order masked implementations with different noise levels and training trace numbers. The results demonstrate that monomials with smaller output size are more vulnerable. Moreover, with the increase (resp. decrease) in noise level (resp. training trace number), the resistance difference of these monomials becomes more significant. In addition, we obtain similar results through simulated experiments on second-order masked scenario. In practical experiments based on an ARM Cortex-M4 architecture, we collect power and electromagnetic traces in consideration of low and high noise levels. The results show that the number of required traces for targeting the S-Box output is at least three times as much that for targeting the weakest monomial.

Miniature coiled artificial muscle for wireless soft medical devices.

Wireless small-scale soft-bodied devices are capable of precise operation inside confined internal spaces, enabling various minimally invasive medical applications. However, such potential is constrained by the small output force and low work capacity of the current miniature soft actuators. To address this challenge, we report a small-scale soft actuator that harnesses the synergetic interactions between the coiled artificial muscle and radio frequency–magnetic heating. This wirelessly controlled actuator exhibits a large output force (~3.1 N) and high work capacity (3.5 J/g). Combining this actuator with different mechanical designs, its tensile and torsional behaviors can be engineered into different functional devices, such as a suture device, a pair of scissors, a driller, and a clamper. In addition, by assuming a spatially varying magnetization profile, a multilinked coiled muscle can have both magnetic field–induced bending and high contractile force. Such an approach could be used in various future untethered miniature medical devices.

The effect of ion chamber volume on intensity-modulated radiotherapy small field dosimetry

The use of appropriate equipment during the measurements required for a treatment planning system (TPS) directly affects the quality of treatment. The present study investigates the effect of small field output factors (OF) obtained with ion chambers of different volumes on intensity-modulated radiotherapy (IMRT) treatment plans. Three different beam models (BM65, BM13, BM04) were created at TPS using small fields OFs measured by ion chambers with three different volumes, i.e. 0.65, 0.13 and 0.04 cc respectively. IMRT plans with the same features were designed for these models. The difference between the calculated and measured doses at dose distributions for each IMRT plan was investigated using point-dose measurement and gamma index method. The OF values obtained with a 0.65 cc ion chamber were significantly different, especially in small fields. The greatest difference in point-dose measurements made in IMRT plans was observed in the plans produced in the BM65 beam model. There was no significant difference in gamma passing rate (GPR) values in 2D array measurements. Inaccurate OF values obtained during small-field measurements is one of the important parameters that affect dosimetric accuracy. Therefore, using different dosimetric methods in quality assurance during TPS commissioning may allow to detect measurement errors, especially in small-field measurements.

Acceleration of Infrared Target Detection via Efficient Channel Pruning

Deployment of modern detection models is difficult for infrared target detection used in robot vision systems due to their heavy computational burden. To alleviate this situation, a simple but efficient channel pruning method is proposed for model acceleration. Specifically, a soft-gated module combined with batch normalization (SGBN) is designed as a standalone layer to substitute the standard batch normalization (BN) layer during training. The conversion between SGBN and BN is easy, and the training overhead introduced is almost negligible after replacement. By controlling the sparsity of the scaling factor in SGBN, unimportant channels with small output are blocked automatically and globally, which is simultaneous with model training. Removing these redundant channels no longer requires fine-tuning, thus significantly speeding up the pruning process. Experiments of pruning different detection models on the infrared dataset show the effectiveness of our method. For example, the parameters and FLOPs of pruned CetnerNet are reduced by 72.70% and 40.20%, respectively, without accuracy loss. The inference speed on the CPU is 12.01ms faster. Extended studies on the classification task also demonstrate its great potential when transferring to other applications.

Effect of inaccurate small field output factors on brain SRS plans

External beam radiotherapy often includes the use of field sizes 3 × 3 cm2 or less, which can be defined as small fields. Dosimetry is a difficult, yet important part of the radiotherapy process. The dosimetry of small fields has additional challenges, which can lead to treatment inconsistencies if not done properly. Most important is the use of an appropriate detector, as well as the application of the necessary corrections. The International Atomic Energy Agency and the American Association of Physicists in Medicine provide the International Code of Practice (CoP) TRS-483 for the dosimetry of small static fields used in external MV photon beams. It gives guidelines on how to apply small-field correction factors for small field dosimetry. The purpose of this study was to evaluate the impact of inaccurate small-field output factors on clinical brain stereotactic radiosurgery plans with and without applying the small-field correction factors as suggested in the CoP. Small-field correction factors for a Varian TrueBeam linear accelerator were applied to uncorrected relative dose factors. Uncorrected and corrected clinical plans were created with two different beam configurations, 6 MV with a flattening filter (6 WFF) and 6 MV without a flattening filter (6 FFF). For the corrected plans, the planning target volume mean dose was 1.6 ± 0.9% lower with p < 0.001 for 6 WFF and 1.8 ± 1.5% lower with p < 0.001 for 6 FFF. For brainstem, a major organ at risk, the corrected plans had a dose that was 1.6 ± 0.9% lower with p = 0.03 for 6 WFF and 1.8 ± 1.5% lower with p = 0.10 for 6 FFF. This represents a systematic error that should and can be corrected.

Optimal Rate List Decoding over Bounded Alphabets Using Algebraic-geometric Codes

We give new constructions of two classes of algebraic code families that are efficiently list decodable with small output list size from a fraction 1-R-ε of adversarial errors, where R is the rate of the code, for any desired positive constant ε. The alphabet size depends only ε and is nearly optimal. The first class of codes are obtained by folding algebraic-geometric codes using automorphisms of the underlying function field. The second class of codes are obtained by restricting evaluation points of an algebraic-geometric code to rational points from a subfield . In both cases, we develop a linear-algebraic approach to perform list decoding, which pins down the candidate messages to a subspace with a nice “periodic” structure. To prune this subspace and obtain a good bound on the list size, we pick subcodes of these codes by pre-coding into certain subspace-evasive sets that are guaranteed to have small intersection with the sort of periodic subspaces that arise in our list decoding. We develop two approaches for constructing such subspace-evasive sets. The first is a Monte Carlo construction of hierearchical subspace-evasive (h.s.e.) sets that leads to excellent list size but is not explicit. The second approach exploits a further ultra-periodicity of our subspaces and uses a novel construct called subspace designs , which were subsequently constructed explicitly and also found further applications in pseudorandomness. To get a family of codes over a fixed alphabet size, we instantiate our approach with algebraic-geometric codes based on the Garcia–Stichtenoth tower of function fields. Combining this with pruning via h.s.e. sets yields codes list-decodable up to a 1-R-ε error fraction with list size bounded by O (1/ε), matching the existential bound for random codes up to constant factors. Further, the alphabet size can be made exp ( Õ (1/ε 2 )), which is not much worse than the lower bound of exp (Ω (1/ε)). The parameters we achieve are thus quite close to the existential bounds in all three aspects (error-correction radius, alphabet size, and list size) simultaneously. This construction is, however, Monte Carlo and the claimed list-decoding property only holds with high probability. Once the code is (efficiently) sampled, the encoding/decoding algorithms are deterministic with a running time O _ε ( N c ) for an absolute constant c , where N is the code’s block length. Using subspace designs instead for the pruning, our approach yields the first deterministic construction of an algebraic code family of rate R with efficient list decoding from 1-R-ε fraction of errors over an alphabet of constant size exp (Õ(1/ε 2 )). The list-size bound is upper bounded by a very slowly growing function of the block length N ; in particular, it is at most O(log ( r ) N ) (the r th iterated logarithm) for any fixed integer r . The explicit construction avoids the shortcoming of the Monte Carlo sampling at the expense of a slightly worse list size.

The impact of additional injected signals on the stability and bandwidth of the quantum cascade lasers with external cavities

- In recent years, special attention has been paid to the injection lock of quantum cascade lasers, which leads to the improvement of their small signal properties and output power. In this paper, the operation of an injection-locked quantum cascade laser including the output characteristics and modulation response has been investigated. By using one external cavity for optical lock, the resulted structure has complexities may cause instability of a laser that limit the use of this system. In this paper, for the first time, to solve this problem, an optical self-locking system was proposed and the properties of laser under these conditions were investigated. By adding a second external cavity to a single external cavity laser, output power will reach a constant value. The output power of the single cavity laser in free-running mode was about 400 mw while the output power of the laser with two external cavities has been increased to 700 mw. In addition to stabilizing the output power, we also see an increase in bandwidth. We found that for different lengths and reflectivity, the output power of the proposed one external cavity laser in free-running mode does not reach a fixed value and even in some cases, it becomes unstable. But by adding a second cavity to the laser in the free-running mode, it will be able to produce a stable laser with constant output power. Adding external cavities can be used as an effective tool to improve frequency stability or increase bandwidth.

A 15 mV-input and 71%-efficiency boost converter with 22 mV output ripple for thermoelectric energy harvesting application

This paper presents a self-startup and ultra-low-voltage boost DC–DC converter for the thermoelectric energy harvesting application. A two-stage auxiliary boost startup circuit with a multi-stage voltage multiplier and a large duty cycle circuit is adopted to achieve a minimum self-startup voltage of 155 mV. And the system can sustain the operation at a 15 mV input. The maximum power point tracking (MPPT) with a combination of coarse and fine frequency tuning is proposed to improve the tracking accuracy with small output ripples of 22 mV. Moreover, the zero current switching (ZCS) scheme combined with the MPPT achieves a peak end-to-end efficiency of 71%, providing a regulated 1.25V output with a maximum power of 540 μW.

A Review on Security and Privacy Issues in IoT Devices

In our everyday lives, the IoT is everywhere. They are used for the monitoring and documentation of environmental improvements, fire safety and even other useful roles in our homes, hospitals and the outdoors. IoT-enabled devices that are linked to the internet transmit and receive a large amount of essential data over the network. This provides an opportunity for attackers to infiltrate IoT networks and obtain sensitive data. However, the risk of a loss of privacy and security could outweigh any of these benefits. Many tests have been carried out in order to solve these concerns and find a safer way to minimize or remove the effect of IoT technologies on privacy and security practices in order to protect them. The issue with IoT devices is that they have small output modules, making it impossible to adapt current protection methods to them. This constraint necessitates the presentation of lightweight algorithms that enable IoT devices. In this article, investigated the context and identify different safety, protection, and approaches for securing components of IoT-based ecosystems and systems, as well as evolving security solutions. In addition, several proposed algorithms and authentication methods in IoT were discussed in order to avoid various types of attacks while keeping the limitations of the IoT framework in mind. Also discuss some hardware security in IoT devices.

Small Field Output Factor Measurement and Verification for Cyberknife Robotic Radiotherapy and Radiosurgery System Using 3D Polymer Gel, Ionization Chamber, Diode, Diamond and Scintillator Detectors, Gafchromic Film and Monte Carlo Simulation

Small Field Output Factor Measurement and Verification for Cyberknife Robotic Radiotherapy and Radiosurgery System Using 3D Polymer Gel, Ionization Chamber, Diode, Diamond and Scintillator Detectors, Gafchromic Film and Monte Carlo Simulation

A Small Wind Turbine Output Model for Spatially Constrained Remote Island Micro-Grids

A Small Wind Turbine Output Model for Spatially Constrained Remote Island Micro-Grids

Design and Analysis of a 2-D Piezoelectric Platform Based on Three-Stage Amplification and L-Shaped Guiding

In piezoelectric micro-positioning platforms, the displacement amplification mechanism can solve the small output displacement of the platform; the displacement coupling will also increase when the displacement is amplified. To solve the problem of multistage displacement amplification and displacement coupling after multistage displacement amplification, this study proposes a two-dimensional piezoelectric platform based on three-stage amplification and L-shaped guiding. First, the structure of the two-dimensional piezoelectric platform is designed and its working principle is described. Next, the two-dimensional piezoelectric platform is analyzed theoretically, and the static and dynamic characteristics of the structure are analyzed by the finite element method. Finally, a prototype of the two-dimensional piezoelectric platform is fabricated, and the theoretical and simulation results are analyzed experimentally. The experimental results reveal that the platform has a motion range of 31.8 μm × 41 μm. The multistage displacement amplification ratio is 21.8, and the displacement coupling error is less than 4.2%. The positioning error of the closed-loop control platform is less than 0.5%, and the trajectory tracking error is less than 1.6%. Compared with the traditional piezoelectric micro-positioning platform, the three-stage amplification and L-shaped guiding mechanism can effectively improve the displacement magnification and decoupling performance of the piezoelectric micro-positioning platform as well as the positioning ability and trajectory tracking ability of the platform under closed-loop control, which is expected to be utilized in fields such as multi-stage amplification micro-positioning platforms and dynamic optical systems.

Examination on Evaluation Method of Small Output Organic Rankine Cycle Equipped with the Scroll Turbine

Examination on Evaluation Method of Small Output Organic Rankine Cycle Equipped with the Scroll Turbine

Comprehensive Review of KY Converter Topologies, Modulation and Control Approaches With Their Applications

In current scenario, the challenging task in designing a DC-DC converter has high voltage gain and small output ripple waves, which researchers deal with highly complicated. Because of its topological and Continuous Conduction Mode (CCM), the KY converters have developed a better converter than all the traditional DC-DC converters to overcome this intricacy of voltage transfer gain and output ripple waves. The KY converters had comparative and various qualities when compared with the boost converter with Synchronous Rectifier (SR). The KY converter is used in photovoltaic and sustainable power applications, which are examined in this study. KY converter incorporates mode-1 and mode-2 operation and its types, for example, one plus D and one plus 2D where the KY can deliver the N <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> type of KY converters. This article provides a comprehensive review and investigation of the KY converters, which incorporates their topology with control methodologies, Pulse Width Modulation (PWM) techniques, working activity of KY converters, and types for mode-1 and -2; it interprets the few strategies the KY converter is executed and its applications.

Measuring small field profiles and output factors with a stemless plastic scintillator array.

To fabricate a 1D stemless plastic scintillation detector (SPSD) array using organic photodiodes and to use the detector to measure small field profiles and output factors. An organic photodiode array was fabricated by spin coating a mixture of P3HT and PCBM organic semiconductors onto an ITO-coated glass substrate and depositing aluminum top contacts. Four bulk scintillators of various dimensions were placed on top of the photodiode array. A fifth scintillator was used that had been segmented by laser etching and the septa filled with black paint. Each detector array was first calibrated using a reference field of 95cm SSD, 5cm depth, and 10×10 cm2 field size for a 6 MV photon beam. After calibration, profiles were measured for three small field sizes: 0.5×0.5 cm2 , 1×1 cm2 , and 2×2 cm2 . Using the central pixel of the array, output factors were measured for field sizes of 0.5×0.5 cm2 to 25×25 cm2 . Small field profiles were compared to film measurements and output factors compared to ion chamber measurements. The segmented scintillator measured profiles that were in good agreement with film for all three field sizes. Output factors agreed to within 1.2% of ion chamber over the field size range of 1×1 cm2 to 25×25 cm2 . At 0.5×0.5 cm2 the segmented scintillator underestimated the output factor compared to film and a microDiamond detector. Bulk scintillators failed to produce a good agreement with film for measured profiles and deviations from ion chamber for output factors were apparent at field sizes below 5×5 cm2 . In comparison to a bulk scintillator of dimensions 5×5×0.5 cm3 the etched scintillator saw a reduction of 5.1, 7.1, and 10.5 times the signal for field sizes of 0.5×0.5 cm2 , 1×1 cm2 , and 2×2 cm2 , respectively. The reduction of signal comes from reduced cross-talk that was present in all of the bulk scintillator geometries to various degrees. A 1D SPSD array was demonstrated with various scintillator designs. The etched scintillator array demonstrated excellent small field profile measurements when compared to film and output factors (down to 1×1cm2 field size) when compared to micro ion chamber and diamond detector measurements.

A Two-Phase Three-Level Buck Converter With Cross-Connected Flying Capacitors for Inductor Current Balancing

The two-phase operation of a dc-dc converter has several benefits, when compared with the single phase, including higher efficiency, smaller ripple, faster response, etc. However, it suffers from unbalanced currents between the two phases. This article presents a two-phase three-level buck converter with cross-connected flying capacitors (X-C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FLY</sub> ). The proposed converter suppresses the unbalanced inductor currents in a two-phase operation, through the alternate connection of flying capacitors across the branches. Meanwhile, two-phase and three-level techniques help to achieve a fast transient response and a small output ripple. In addition, we derive the transfer function of the proposed generalized multiphase three-level buck converter with interconnected C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FLY</sub> for analysis, and design accordingly its power stage and feedback loop. Finally, we validate the proposed converter through the fabrication in a 65 nm CMOS GP process. It achieves a low unbalanced current close to 5 mA and a small output ripple of 50 mV for a load current around 110 mA, and a peak efficiency of about 86%.

Simulations of hybrid charge-sensing single-electron-transistors and CMOS circuits

Single-electron transistors (SETs) have been extensively used as charge sensors in many areas, such as quantum computations. In general, the signals of SETs are smaller than those of complementary metal–oxide–semiconductor (CMOS) devices, and many amplifying circuits are required to enlarge the SET signals. Instead of amplifying a single small output, we theoretically consider the amplification of pairs of SETs, such that one of the SETs is used as a reference. We simulate the two-stage amplification process of SETs and CMOS devices using a conventional SPICE (Simulation Program with Integrated Circuit Emphasis) circuit simulator. Implementing the pairs of SETs into CMOS circuits makes the integration of SETs more feasible because of direct signal transfer from the SET to the CMOS circuits.

Fault detection for uncertain nonlinear systems via recursive observer and tight threshold

This paper presents an fault detection (FD) method for a class of uncertain nonlinear systems with unmatched nonlinear fault functions and disturbances. A recursive FD observer is designed with predetermined and small output estimation error. The nonlinear observer gain function is achieved by introducing predetermined output estimation accuracy-dependent nonnegative functions. Combining Lyapunov functions, it is shown that the absolute value of the residual signal is equal or lesser than tight threshold before fault occurrence. The FD scheme is proposed following fault detectability analysis, simulation example indicates the validity of the proposed method.

All-in-One High-Power-Density Vibrational Energy Harvester with Impact-Induced Frequency Broadening Mechanisms.

This paper proposes an electrostatic-piezoelectric-electromagnetic hybrid vibrational power generator with different frequency broadening schemes. Both the nonlinear frequency broadening mechanisms and the synergized effect of the electrostatic-piezoelectric-electromagnetic hybrid structures are investigated. The structure and performance of the composite generator are optimized to improve the response bandwidth and performance. We propose that the electrostatic power generation module and the electromagnetic power generation module be introduced into the cantilever beam to make the multifunctional cantilever beam, realizing small integrated output loss, high output voltage, and high current characteristics. When the external load of the electrostatic power generation module is 10 kΩ, its peak power can reach 3.6 mW; when the external load of the piezoelectric power generation module is 2 kΩ, its peak power is 2.2 mW; and when the external load of the electromagnetic power generation module is 170 Ω, its peak power is 0.735 mW. This means that under the same space utilization, the performance is improved by 90%. Moreover, an energy management circuit (ECM) at the rear end of the device is added, through the energy conditioning circuit, the device can directly export a 3.3 V DC voltage to supply power to most of the sensing equipment. In this paper, the hybrid generator’s structure and performance are optimized, and the response bandwidth and performance are improved. In general, the primary advantages of the device in this paper are its larger bandwidth and enhanced performance.