Performance Of Prototype Research Articles

Rechargeable Lithium Metal Pouch Cell Development

Commercially available Li-ion batteries using graphite or graphite-silicon blended anodes are currently approaching a cell level specific energy of 300 Wh kg−1. The use of lithium metal instead as an anode an intriguing possibility to further increase cell level specific energies to 400 Wh kg−1 and beyond. Lithium is an ideal anode because it is the lightest metal and highly electronegative. However, attempts to commercialize cells using lithium metal anodes have been slowed by poor cycle life and safety issues. This is because nonuniform lithium plating leads to the growth of dendrites that cause loss of active lithium and can eventually lead to internal cell shorts. Safe cell cycle life must be improved to 50-100 cycles for special purpose applications like unmanned aerial vehicles, >300 cycles for portable power applications and >1000 cycles for electric vehicle applications.The performance of prototype cells developed at EaglePicher Technologies using lithium metal anode will be highlighted. The figure below on the left shows the specific discharge energy of a 2.5 Ah prototype pouch cell using a lithium anode, high nickel cathode and nonaqueous electrolyte. The cell demonstrates an extremely high specific energy of >400 Wh kg−1 at low rates. The effect of electrolyte on capacity retention is shown in the figure below on the right. The optimized electrolyte demonstrates good retention to >50 cycles. This presentation will focus on design considerations for pouch cells with lithium anodes, as well as improving the cycle life and safety characteristics of these cells. Prototype performance data including cycle life, rate capability, temperature effects and safety testing will be presented.EaglePicher Technologies would like to acknowledge the US Army DEVCOM C5ISR Center in Aberdeen Proving Ground, Maryland for funding this research. Figure 1

Design framework for DEM-supported prototyping of grabs including full-scale validation

The design ofmachinery for handling granular materials relies mainly on empirical methods and in-house engineering knowledge. This traditional approach provides incremental improvements that are often limited. Advancements in simulation and optimization can offer a promising alternative approach. Most of the research involved in improving or optimizing equipment design does not include the realistic performance of the new prototype and as such it is uncertain that the predicted performance is also guaranteed in practice.In this study, a design framework for a new generation of machinery handling granular materials, grabs, has been established that includes a full-scale validation step.This has been proven to lead to a breakthrough in equipment design. This design framework uses a co-simulation between Discrete Element Method (DEM) and Multi Body Dynamics (MBD), thus, capturing operational conditions in full-scale. The DEM simulation supported design step integrated as the main step to generate new prototypes. The performance of the prototype is evaluated by conducting full-scale experiments, thus validating the adequacy of the new design as well as the accuracy of the co-simulation. Through this a full design cycle has been fulfilled and a validated model has been achieved that is independent of specific design configurations.

An innovative torsional vibration absorber of vehicle powertrain system: Prototype design, performance test, and control experiment

A dynamic vibration absorber can effectively reduce the vibration of a mechanical system, and designing a new type of torsional vibration absorber to reduce the torsional vibration of the vehicle powertrain system and establishing relevant experiments to test its vibration reduction performance are necessary. This article presents a detailed design and manufacturing process of an innovative torsional vibration absorber with magnetorheological elastomers (MREs) as its core intelligent element. A series of experiments are carried out to evaluate the vibration reduction performance of the new vibration absorber. A vibration reduction performance experiment with a torsional vibration exciter is used to test the vibration transmissibility of the vibration absorber, and the frequency shift range is identified. An engine vibration reduction performance experiment is carried out to verify the feasibility of the vibration absorber in actual powertrain systems, and its good vibration reduction effect is also proven by comparative experiments. A semi-active control experiment of the vibration absorber is performed to verify the reliability of the programmable power supply and the conductive slip ring and prove the effectiveness of the dominant external excitation frequency identification method and vibration absorber control strategy.

An Interactive WebGIS Framework for Coastal Erosion Risk Management

The Italian coastline stretches over about 8350 km, with 3600 km of beaches, representing a significant resource for the country. Natural processes and anthropic interventions keep threatening its morphology, moulding its shape and triggering soil erosion phenomena. Thus, many scholars have been focusing their work on investigating and monitoring shoreline instability. Outcomes of such activities can be largely widespread and shared with expert and non-expert users through Web mapping. This paper describes the performances of a WebGIS prototype designed to disseminate the results of the Italian project Innovative Strategies for the Monitoring and Analysis of Erosion Risk, known as the STIMARE project. While aiming to include the entire national coastline, three study areas along the regional coasts of Puglia and Emilia Romagna have already been implemented as pilot cases. This WebGIS was generated using Free and Open-Source Software for Geographic information systems (FOSS4G). The platform was designed by combining Apache http server, Geoserver, as open-source server and PostgreSQL (with PostGIS extension) as database. Pure javascript libraries OpenLayers and Cesium were implemented to obtain a hybrid 2D and 3D visualization. A user-friendly interactive interface was programmed to help users visualize and download geospatial data in several formats (pdf, kml and shp), in accordance with the European INSPIRE directives, satisfying both multi-temporal and multi-scale perspectives.

Leaf Image Classification with the Aid of Transfer Learning: A Deep Learning Approach

Background: Crop diseases are a primary hazard to nutrient safety, which proves to be a serious problem in many places in the world due to the unavailability of essential aid. Typically agriculturalists or specialists perceive the plants with a naked eye for detection and identification of an illness. Machine vision models, in specific Convolutional Neural Networks (CNNs) have directed an impact in feature extraction to a greater extent. Since 2015, numerous solicitations for the automatic classification and recognition of crop illnesses have been established. Methods: In this paper, we proposed, analyzed, and assessed various state-of-the-art models proposed over a decade. These models are pre-trained with the finest parameters where we modeled a design-oriented method with numerous leaf-images and classified them into infection and healthy class for each type of leaf independently. Results: Through our examination, we concluded that VGG models stand-alone with many cited prototypes and give on par results. As declared, these VGG models (VGG16 and VGG19) are utilized for feature extraction, and further, we augmented a set of dense layers and train them consequently for classification. The performances of various machine vision prototypes were pictorially perceived and their sophisticated architecture is not only capable of extracting detailed features but also repressed many loop-holes. The performance is assessed and computed for several types of leaf images and the accuracy scores attained were more than 97.5% for VGG16 and 96.72% for VGG19. Conclusion: AUC-ROC curves were portrayed to illustrate its inspiration in defining an accurate classification where VGG16 and VGG19 have at least 96.6% and 95% area under the curve (AUC) which resembles their robustness.

A reconfigurable flexible fractal‐based monopole antenna for portable applications

SummaryDesign of a fractal printed circuit antenna structure for portable applications is presented in this paper. The proposed antenna consisted of a modified Hilbert patch printed on a flexible polyamide substrate. The antenna is surrounded with a defected electromagnetic bandgap (EBG) open loop. A parametric study based a numerical analysis is invoked to refine the proposed antenna performance. The proposed antenna is fabricated on polymer substrate with dimensions of 50 × 60 × 0.3 mm3. The proposed antenna performance is tested experimentally and compared to the simulated results from a commercial software package based on Computer Simulation Technology Microwave Studio (CST MW). The experimental results are found to agree well with simulated results. It is found that the proposed antenna design suites the applications of the frequency bands of UHF and ISM portable systems. The antenna shows two bandwidths from 0.8 to 1 GHz and from 2.3 to 2.6 GHz with average gain of around 3.1 and 7 dBi, respectively. The antenna performances are conducted based on analytical and numerical simulations. The fabricated prototype performances are measured experimentally to show excellent agreement with the simulated results. Finally, it is found that the proposed antenna frequency resonance and bandwidth are insignificantly affected when mounted in close to the human body; therefore, it would be excellent candidate to be in use with biomedical applications.

Design and performance of a hyperspectral camera for full-face in vivo imaging.

Red, green, blue color photography is a mature technology and a powerful tool for the evaluation and understanding of the way an object reflects light and its related optical properties, but color photography fails to give a complete picture of these effects due to its inherent lack of spectral resolution. In this work, we update the L'OREAL reference device for skin color measurement, the Chromasphere, by replacing its current color camera system with an imaging spectrometer. This imaging spectrometer must provide a spatial resolution on par with the previous color cameras and a spectral resolution commensurate with a spectroradiometer while also achieving a time resolution suitable for in vivo studies of the human face. Due to these requirements, common spatial scanning techniques are not suitable for this application, and so we utilized a spectral-scanning approach based on a tunable liquid-crystal birefringent filter. We present the design and performance tests of a working prototype that is capable of measuring the spectrum in each of 4 MP with a nominal spectral resolution of 10nm across the wavelength range from 420 to 730nm in a total imaging time of less than 10s. We cross-compared the spectral and color measurements obtained with this prototype, an industry-standard spectroradiometer, and a charge-coupled device color camera in order to assess the prototype's performance, and the results of this comparison show that our prototype is capable of taking spectral measurements near enough in quality to those of a spectroradiometer to successfully bridge the divide between such devices and conventional color cameras. Doing so, this instrument opens new possibilities for studies of complex in vivo phenomena that neither non-imaging spectrometers nor conventional cameras can pursue.

A new magnetic melt spinning device for patterned nanofiber

The size and morphology of nanofibers directly determine their application scope and performance, while regular patterned fibers further demonstrate their superior performance in the field of sensors and biomaterials. Melt electrospinning enables controlled deposition of fibers and is currently one of the most important means of preparing patterned fibers. However, due to the existence of high-voltage electric field, melt electrospinning has safety problems such as partial discharge and electric field breakdown, coupled with the charge rejection on the fiber surface, which seriously affects the positioning deposition of fibers and makes it difficult to obtain regular patterned fibers, greatly limiting the application areas and application effects of patterned fibers. Therefore, the improvement and innovation of the spinning process is particularly urgent. Based on material-field model and contradiction matrix of TRIZ theory, the problems of melt electrospinning device are systematically analyzed. The technical conflicts are solved by the inventive principles. A three-dimensional mobile magnetic melt spinning device model is constructed, a magnetic spinning test prototype is developed, and the prototype performance and influencing factors are studied by fiber morphology. The results show the following: (1) Replacing electrostatic fields with permanent magnetic fields can fundamentally avoid safety hazards such as electric field breakdown. (2) The magnetic field force on the molten polymer fluid can generate enough stretching force to overcome the surface tension and form fibers. (3) The fibers are deposited without a whipping instability phase similar to the electrospinning process, allowing easy preparation of regular patterned fibers. (4) The planar motion of the collector creates additional stretching effect on the fibers, which can further reduce the fiber diameter. (5) In magnetic spinning, no external high-voltage power supply is required, enabling the portability of the device. The results of this paper can provide a new method for preparing nanofibers with patterned morphology.

Performance evaluation of an absorption heat transformer for industrial heat waste recovery using the characteristic equation

In this paper we report on new experimental results of an absorption heat transformer. In order to have a concise view on the whole performance field the characteristic equation model, a novel version of ideas from the 80ies of the last century is developed. In the model insight from recent research on absorption chillers is used. The 40 kW prototype implements a single effect absorption cycle working with water as refrigerant and an aqueous LiBr solution as the solvent. As a novelty, the parameter set of the characteristic equation model has been obtained from the cycle analysis of the device based on the measurements of one single operating point. The resulting model predicts the prototype performance for driving heat temperature levels of low temperature industrial waste heat sources (60–100 °C), with variations of the temperature of the useful upgraded between 90 and 138 °C that result in gross temperature lifts (GTL) between 20 and 55 K. The measured COP values are between 0.30 and 0.48. An additional regression developed after evaluating the deviations from the model assumptions reduces the uncertainty of the model. The uncertainties for COP and upgraded heat flow rate predictions are below 11% (R2 = 0.812) and 4% (R2 = 0.918) respectively.

Ex Vivo Performance of a Flexible Microwave Ablation Antenna.

In this study, we investigate the performance of a flexible microwave ablation antenna for generating localized ablation zones. We designed a helical dipole antenna to operate at 1.9GHz in egg white and liver. Semi-rigid prototypes of the antenna were fabricated and used to perform ablation experiments in egg white and perfused liver. Pulsed and continuous-wave power deliveries at different power levels were used. Flexible prototypes of the antenna were fabricated and used to perform ex vivo ablation experiments in perfused liver. Pulsing was effective in reducing the shaft heating of semi-rigid cables. The antenna was capable of producing substantial ablation zones in perfused liver. Typical diameters (perpendicular to the antenna axis) of generated ablation zones with semi-rigid antennas in egg white and perfused liver were 30mm and 20mm, respectively. The flexible antenna had a good impedance match while bent. Average diameter of generated ablation zones by the flexible antenna with 10-W continuous-wave experiments in perfused liver was 26mm. No significant difference was observed between the performances of semi-rigid and flexible prototypes. The flexible helical dipole antenna is capable of maintaining its good impedance match while bent and can generate substantial ablation zones in presence of perfusion. The proposed flexible antenna is promising for minimally invasive treatment of tumors that are otherwise inaccessible by rigid antennas. One example is lung where a catheter-based deployment of the flexible antenna into the tumor via airways may substantially reduce risks associated with using rigid antennas.

Low-Cost Radiant Heater for Rapid Response, High-Temperature Heating

High-temperature processing has an irreplaceable role in many research and industrial applications. Despite remarkable development spanning over a century, the pursuit of even higher thermal flux density and more rapid thermal transients has not slowed down. As part of the ongoing energy evolution, many industrial applications are transitioning from direct combustion of fossil fuels as primary energy sources to increasing electrification, capable of adapting to renewable power grids. Thus, there is an emerging need for electrical heaters that can replace burners and supply the heat demand, especially at the highest temperatures. In this study, we report on a radiant heater design that can achieve cyclic heating/cooling rates of up to 400 K min–1 and a temperature range in excess of 1,800 K, comparable to those of commercial infrared gold image furnaces, at high surface and volumetric power densities. The heater consists of a modular unit of incandescent tungsten filament and is enclosed in an evacuated ceramic envelope, chemically inert, tolerant of thermal shock, and impervious to gasses. The material and manufacture cost of such heaters, which is estimated at ∼$0.05/W, is less than 0.03% of that for infrared gold image furnaces, which is at >$2/W. Tests of more than 10,000 demanding cycles (high temperature and high heating/cooling rate) over 350 h of total operational time and in different temperature ranges confirm the robust performance of radiant heater prototypes. The design is widely applicable to high-temperature reactor and furnace designs. In thermochemistry research and practice, these radiant heaters could offer multiple benefits compared to solar simulators, lasers, infrared gold furnaces, ceramic heaters, or direct concentration of solar input.

A 20-gauge active needle design with thin-film printed circuitry for interventional MRI at 0.55T.

This work aims to fabricate RF antenna components on metallic needle surfaces using biocompatible polyester tubing and conductive ink to develop an active interventional MRI needle for clinical use at 0.55 Tesla. A custom computer numeric control-based conductive ink printing method was developed. Based on electromagnetic simulation results, thin-film RF antennas were printed with conductive ink and used to fabricate a medical grade, 20-gauge (0.87 mm outer diameter), 90-mm long active interventional MRI needle. The MRI visibility performance of the active needle prototype was tested in vitro in 1 gel phantom and in vivo in 1 swine. A nearly identical active needle constructed using a 44 American Wire Gauge insulated copper wire-wound RF receiver antenna was a comparator. The RF-induced heating risk was evaluated in a gel phantom per American Society for Testing and Materials (ASTM) 2182-19. The active needle prototype with printed RF antenna was clearly visible both in vitro and in vivo under MRI. The maximum RF-induced temperature rise of prototypes with printed RF antenna and insulated copper wire antenna after a 3.96 W/kg, 15 min. long scan were 1.64°C and 8.21°C, respectively. The increase in needle diameter was 98 µm and 264 µm for prototypes with printed RF antenna and copper wire-wound antenna, respectively. The active needle prototype with conductive ink printed antenna provides distinct device visibility under MRI. Variations on the needle surface are mitigated compared to use of a 44 American Wire Gauge copper wire. RF-induced heating tests support device RF safety under MRI. The proposed method enables fabrication of small diameter active interventional MRI devices having complex geometries, something previously difficult using conventional methods.

Hot isostatic pressing assisted diffusion bonding for application to the Super Proton Synchrotron internal beam dump at CERN

The new generation internal beam dump of the Super Proton Synchrotron (SPS) at CERN will have to dissipate approximately 270 kW of thermal power, deposited by the primary proton beam. For this purpose, it is essential that the cooling system features a very efficient heat evacuation. Diffusion bonding assisted by Hot Isostatic Pressing (HIP) was identified as a promising method of joining the cooling circuits and the materials of the dump's core in order to maximise the heat transfer efficiency. This paper presents the investigation of HIP assisted diffusion bonding between two CuCr1Zr blanks enclosing SS 316L tubes and the realisation of a real size prototype of one of the dump's cooling plate, as well as the assessments of its cooling performance under the dumps most critical operational scenarios. Energy-dispersive X-ray (EDX) spectroscopy, microstructural analyses, measurements of thermal conductivity and mechanical strength were performed to characterize the HIP diffusion bonded interfaces (CuCr1Zr-CuCr1Zr and CuCr1Zr-SS316L). A test bench allowed to assess the cooling performance of the real size prototype. At the bonded interface, the presence of typical diffusional phenomena was observed. Moreover, measured tensile strength and thermal conductivity were at least equivalent to the lowest ones of the materials assembled and comparable to its bulk properties, meaning that a good bonding quality was achieved. Finally, the real size prototype was successfully tested with an ad-hoc thermal test bench and with the highest operational thermal power expected in the new generation SPS internal beam dump.

Numerical Analysis and Experimental Investigation on a Novel Piezoelectric-Actuated Rail-Type Mobile Platform

A novel piezoelectric-actuated rail-type mobile platform is proposed in this article, which has potential application in the inspection and maintenance tasks of the Tokamak vacuum vessel as it holds good environmental adaptability to extreme environments, such as strong magnetic fields, high vacuum, and high temperature. The rail-type piezoelectric-actuated mobile platform consists of a rail and a framed piezoelectric actuator operating with two orthogonal bending vibrations. The framed piezoelectric actuator moves on the rail by friction. At first, a semianalytical model is created for the framed piezoelectric actuator utilizing the transfer matrix method in order to reveal its dynamic behavior. Then, the prototype of the proposed framed piezoelectric actuator is manufactured and assembled, and its vibration characteristics are measured to verify the feasibility of the developed transfer matrix model. Additionally, the mechanical output performances of the rail-type mobile platform prototype are investigated experimentally, and it is observed that the maximum speed of the mobile platform prototype reached 384.68 mm/s when the amplitude of the driving voltage is 400 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> , its maximum load-weight to self-weight ratio reached 7.6 when the excitation voltage is 300 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> , its maximum output force is about 1.8 N under the excitation voltage of 400 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> , and the minimum displacement resolution is 4 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m when operated in the stepping mode. Finally, the extreme environment (temperature: 0–120 °C and vacuum: 3×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> –10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> Pa) tests are carried out to measure the output performances of the mobile platform prototype. The results show that the platform prototype is capable of carrying loads in a high-temperature and high-vacuum environment.

Utilization of leaf and fruit extracts of kedondong (Spondias dulcis Forst) as a supporting material for energy conversion in dye sensitized solar cells and electrochemical cells

This study aims to obtain a dye sensitized solar cell (DSSC) prototype and a voltaic cell prototype using the kedondong plant (Spondias dulcis Forst). Kedondong leaves as a source of chlorophyll were deliberately chosen to be in line with the use of kedondong fruit as a material for electrochemical cells, so that two research results could be obtained from the kedondong plant. This research is for the application of scientific development, increasing the added value of kedondong plant, and as support for the use of environmentally friendly energy. Research methods in general are chlorophyll extraction, citric acid isolation, chlorophyll testing, DSSC assembly, electrochemical cell assembly, and performance testing for both DSSC and electrochemical cells. The analysis results show that typical peaks appear for the functional groups in chlorophyll at certain wave numbers. Hydroxyl (-OH) groups appear in the range of 3650 - 3200 cm-1, the C=C group at 1700 - 1500 cm-1, the C-N group at 1350 - 1000 cm-1, and the C-O group at 1300 - 1000 cm-1. Quantitative testing used a UV-Vis spectrophotometer at 645 nm and 633 nm, the results obtained were chlorophyll a was 4.52 mg/L, chlorophyll b was 8.43 mg/L, and total chlorophyll was 12.95 mg/L. The DSSC prototype performance test with a size of only 2.5 cm2, can produce a minimum voltage of 30.1 mV and a maximum of 280 mV. The electrochemical test of kedondong citric acid extract showed that the value of the electric voltage ranged from 121 to 630 mV. Keywords: Kedondong, Chlorophyll, DSSC, Citric acid, Electrochemical cells

Displacement Sensor With Nanometric Resolution Based on Magnetoelectric Effect

Micro-displacement measurement is essential in precision fields, such as precision positioning, micro-vibration control and biological engineering. Conventional sensors have disadvantages of susceptibility to environmental, high cost and difficulty in integration. To address these deficiencies, this paper developed a novel displacement sensor with nanometric resolution based on magnetoelectric effect. Combining equivalent magnetic circuit method and equivalent circuit method for magnetoelectric effect using the nonlinear constitutive parameters, an equivalent circuit model of the proposed sensor is established to analyse and predict the performance of displacement sensor. Then a prototype of sensor based on Terfenol-D/PZT composites is fabricated, and the performance of prototype for dynamic displacement amplitude and static position measurement are tested. The results not only validate the developed equivalent circuit model, but also evidence the potential of magnetoelectric displacement sensor. Especially for dynamic displacement amplitude measurement, the resolution of it is better than 13.27 nm, which is close to or even beyond commercial laser displacement sensor.

Performance of the hematology analyzer XN-31 prototype in the detection of Plasmodium infections in an endemic region of Colombia

Early and accurate diagnosis is critical in reducing the morbidity and mortality associated with malaria. Microscopy (MI) is the current diagnostic gold standard in the field; however, it requires expert personnel, is time-consuming, and has limited sensitivity. Although rapid diagnostic tests for antigen detection (RDTs) are an alternative to diagnosis, they also have limited sensitivity and produce false positive results in detecting recent past infection. The automated hematology analyzer XN-31 prototype (XN-31p) (Sysmex Corporation, Kobe, Japan) is able to identify plasmodium-infected erythrocytes, count parasitemia and perform complete blood-cell counts within one minute. The performance of the XN-31p in diagnosing malaria was evaluated and compared with real-time polymerase chain reaction (qPCR), MI and RDT in an endemic area of Colombia where Plasmodium falciparum and Plasmodium vivax are present. Acute febrile patients were enrolled from July 2018 to April 2019 in Quibdó, Colombia. Malaria diagnoses were obtained from MI and RDT in the field and later confirmed by qPCR. Venous blood samples in EDTA were processed with an XN-31p in the field. Sensitivity, specificity, positive/negative predictive values, and the likelihood ratios of positive and negative tests were calculated with respect to the results from qPCR, MI and RDT. The intraclass correlation coefficient (ICC) and Bland–Altman plot were used to evaluate the concordance in the parasitemia with respect to MI. A total of 1,754 subjects were enrolled. The mean age was 27.0 years (IQR 14–44); 89.6% were Afro-Colombians, 94.3% lived in urban areas and 0.91% were pregnant. With respect to qPCR, the XN-31p showed a sensitivity of 90% (95% CI 87.24–92.34) and a specificity of 99.83% (95% CI 99.38–99.98) in detecting Plasmodium spp.; both parameters were equivalent to those for MI and RDT. Using MI as the reference, the XN-31p showed a sensitivity of 98.09% (95% CI 96.51–99.08), a specificity of 99.83% (95% CI 99.4–99.98), an ICC of 0.85 (95% CI 0.83–0.87) and an average difference of − 3096 parasites/µL when compared with thick-smear MI and an ICC of 0.98 (95% CI 0.97–0.98) and an average difference of − 0.0013% when compared with thin-smear MI. The XN-31p offers a rapid and accurate alternative method for diagnosing malaria in clinical laboratories in areas where P. falciparum and P. vivax cocirculate.

Checking is Believing: Event-Aware Program Anomaly Detection in Cyber-Physical Systems

Securing cyber-physical systems (CPS) against malicious attacks is of paramount importance because these attacks may cause irreparable damages to physical systems. Recent studies have revealed that control programs running on CPS devices suffer from both control-oriented attacks (e.g., code-injection or code-reuse attacks) and data-oriented attacks (e.g., non-control data attacks). Unfortunately, existing detection mechanisms are insufficient to detect runtime data-oriented exploits, due to the lack of runtime execution semantics checking. In this work, we propose Orpheus, a new security methodology for defending against data-oriented attacks by enforcing cyber-physical execution semantics. We first present a general method for reasoning cyber-physical execution semantics of a control program (i.e., causal dependencies between the physical context and program control flows), including the event identification and dependence analysis. As an instantiation of Orpheus, we then present a new program behavior model, i.e., the event-aware finite-state automaton (eFSA). eFSA takes advantage of the event-driven nature of CPS control programs and incorporates event checking in anomaly detection. It detects data-oriented exploits if a specific physical event is missing along with the corresponding event dependent state transition. We evaluate our prototype's performance by conducting case studies under data-oriented attacks. Results show that eFSA can successfully detect different runtime attacks. Our prototype on Raspberry Pi incurs a low overhead, taking 0.0001s for each state transition integrity checking, and 0.063s~0.211s for the cyber-physical contextual consistency checking.

A Preclinical System Prototype for Focused Microwave Breast Hyperthermia Guided by Compressive Thermoacoustic Tomography

As a newly developed technique, focused microwave breast hyperthermia (FMBH) can provide accurate and cost-effective treatment of breast tumors with low side effect. A clinically feasible FMBH system requires a guidance technique to monitor the microwave power distribution in the breast. Compressive thermoacoustic tomography (CTT) is a suitable guidance approach for FMBH, which is more cost-effective than MRI. However, no experimental validation based on a realized FMBH-CTT system has been reported, which greatly hinders the further advancement of this novel approach. We developed a preclinical system prototype for the FMBH-CTT technique, containing a microwave phased antenna array, a microwave source, an ultrasound transducer array and associated data acquisition module. Experimental results employing homogeneous and inhomogeneous breast-mimicking phantoms demonstrate that the CTT technique can offer reliable guidance for the entire process of the FMBH. In addition, small phase noises do not deteriorate the overall performance of the system prototype. The realized preclinical FMBH-CTT system prototype is capable for noninvasive, accurate and low-side-effect breast tumor treatment with effective guidance. The experimentally validated FMBH-CTT system prototype provides a feasible paradigm for CTT guided FMBH, establishes a practical platform for future improvement of this technique, and paves the way for potential clinical translation.

Implementation and validation of a strongly coupled numerical model of a fully passive flapping foil turbine

This paper presents the implementation and validation of a strongly coupled numerical model of a fully passive flapping foil turbine operating at a high Reynolds number. Thanks to a strong fluid–solid coupling strategy, the well known added-mass instability is mitigated while simulating a lightweight flapping foil. The numerical results are first validated in the case of a fixed foil undergoing static stall. The model is then validated with respect to numerical results available in the literature for a heavy flapping foil turbine. Finally, the numerical results of the strongly coupled model are compared to experimental data of a lightweight turbine prototype tested in a confined channel. The numerical results have shown to be in good agreement with the experimental measurements. Indeed, the kinematics and harvesting performances of the turbine prototype have been accurately reproduced by the numerical simulations. Besides, the leading edge vortex shedding observed in the experiments has also been precisely reproduced by the numerical results. The strongly coupled model implemented and validated in the present paper constitutes a useful tool for expanding the parameter space in the search for an optimised design of the fully passive flapping foil turbine.