Dedicated Test Setup Research Articles

An In-Depth Study of Ring Oscillator Reliability under Accelerated Degradation and Annealing to Unveil Integrated Circuit Usage.

The reliability and durability of integrated circuits (ICs), present in almost every electronic system, from consumer electronics to the automotive or aerospace industries, have been and will continue to be critical concerns for IC chip makers, especially in scaled nanometer technologies. In this context, ICs are expected to deliver optimal performance and reliability throughout their projected lifetime. However, real-time reliability assessment and remaining lifetime projections during in-field IC operation remain unknown due to the absence of trustworthy on-chip reliability monitors. The integration of such on-chip monitors has recently gained significant importance because they can provide real-time IC reliability extraction by exploiting the fundamental physics of two of the major reliability degradation phenomena: bias temperature instability (BTI) and hot carrier degradation (HCD). In this work, we present an extensive study of ring oscillator (RO)-based degradation and annealing monitors designed on our latest 28 nm versatile array chip. This test vehicle, along with a dedicated test setup, enabled the reliable statistical characterization of BTI- and HCD-stressed as well as annealed RO monitor circuits. The versatility of the test vehicle presented in this work permits the execution of accelerated degradation tests together with annealing experiments conducted on RO-based reliability monitor circuits. From these experiments, we have constructed precise annealing maps that provide detailed insights into the annealing behavior of our monitors as a function of temperature and time, ultimately revealing the usage history of the IC.

Controlled interlaminar crack initiation in thin notched laminated thermoplastic composites under impact loading: A first step towards unitary layer recovery

The recycling of composite materials is nowadays a major challenge as it is systematically associated with a downcycling due to the reduction of the fiber length. However, recent works demonstrated that the delamination-based recovery of the unitary layers of laminated structures with preserved mechanical properties is possible under dedicated loading conditions. The presented work aims at investigating this innovative process and in particular the interlaminar crack initiation from a straight notch milled in the material by using an impact loading; further crack extension to recover the complete lamina being the following step of the process. A Split Hopkinson Bar setup has been used in a Direct Impact configuration and a dedicated test setup has been implemented to impose translational and rotational kinematics to the impacted side of the tested specimens in order to enable crack initiation and propagation over a few millimeters. Imposing translational kinematics to the impacted side of the specimen has been shown to induce cracks in a reproducible manner. Numerical simulation results explain the more favorable conditions provided by the translational kinematic.

Determination of material properties from tissue samples of low strength and size

Abstract Uniaxial tensile tests are the most common method for investigating the mechanical properties of materials. However, due to the small strength and size of certain materials, larger conventional universal testing machines are sometimes not suitable for performing elongation testing, so dedicated test setups are required. Therefore, the authors developed a testing device to measure the mechanical properties of small, flexible materials, e.g. fragile specimens of the capsular bag of the eye. Also different variants for specimen holders were designed and tested. Initial tests using eggshell membranes as a model material demonstrated the functionality of the test setup at different strain rates.

On the effects of spider-arms vignetting on interferometric measurements of deformable mirrors

The interferometric calibration and measurement of deformable mirrors for adaptive optics are often performed on complex optical system with spider arms. The spider shadows may divide the mirror surface into separate islands on the detector, so the interferometer fails in reconnecting them to a common phase value. The calibration measurements then suffer from such artificial differential pistons across islands, which is converted into a wrong actuator command and in general into a poor calibration. We review the effects of spider arms shadowing as experienced during the optical calibration of large format adaptive mirrors, such as the Large Binocular Telescope and Very Large Telescope ones; we describe the procedures that we tested to cope with these issues and their effectiveness; and we present a laboratory assessment of the effect of such a shadowing with a dedicated test setup. Our work is part of a preparatory activity for the optical test of the European Extremely Large Telescope adaptive mirror M4.

The use of an artificial neural network for acoustic selections headphone filters

The article aims to examine the influence of various acoustic materials on the usable properties of headphones. Acoustic materials act as filters that modify the incident acoustic waves by attenuating specific frequency components of the acoustic signals. They can therefore be called acoustic filters because they affect the frequency response (bandwidth) of the headphones in question. Therefore, the choice of acoustic materials in headphones with a specific design can have a significant impact on their psychoacoustic properties. Calibrating your headphones is critical to ensure they don't amplify, attenuate or introduce any coloration to your frequencies. To address this problem, a dedicated test setup was designed and constructed to evaluate the frequency response of selected headphone models using seven different acoustic materials (acoustic filters). The final selection of the acoustic filter was made using an artificial neural network. The article presents the measurement methodology, and the obtained frequency response measurements were analyzed and compared.

A low-power analog front-end amplifier for SiPM based radiation detectors

A low-power analog front-end amplifier for SiPM based radiation detectors is presented. In particular, an event-driven low-noise charge sensitive amplifier (CSA) is developed in conjunction with a novel charge division scheme by capacitively coupling the SiPM to the CSA so that the SiPM’s linear energy-charge correlation is preserved, while conserving power. Following extensive circuit simulations and design finalization, a test chip containing the presented front-end amplifier has been fabricated in the target 65 nm CMOS technology. The fabricated prototype and the presented SiPM read-out approach have been verified and characterized using a dedicated test setup. An energy resolution of 11.7% is achieved for the 511 keV peak of a Na-22 source and 10.9% for the 662 keV peak of a Cs-137 source, using an onsemi 3 mm × 3 mm SiPM and a LYSO scintillator coupled to the fabricated CSA. The front-end amplifier consumes 350 μW of power, while maintaining linearity across a wide energy range following calibration. Including the active amplifier circuitry, the bias generator section, and the capacitor bank that realizes the feedback capacitor Cfb of the CSA, the front-end amplifier occupies a silicon area of 50,000 μm2, which supports low-power, multi-channel read-out realizations within a small footprint.

First light of MC[formula omitted]-1K, a 250 [formula omitted]m pixel pitch CdTe imaging spectrometer for hard X-ray astronomy

The next generation of hard X-ray space telescopes for astrophysics and solar physics requires the development of focal planes with high detection efficiency above 10 keV and enhanced spectroscopic imaging performance. We designed and produced MC2-1K, the first prototype of a new family of fine pitch hybrid detectors. It consists of a 32 × 32 pixel CdTe semiconductor detector point-to-point connected to the spectroscopic channels of a full-custom ASIC. The ASIC named D2R2 was produced in 2019 in the XFAB 0.18 μm technology and has the same 250 μm pixel pitch as the detector. We demonstrated a median equivalent charge noise of 54 e- RMS, equivalent to an energy resolution of 654 eV at 31 keV for a CdTe detector. We developed an acquisition system where the signals of D2R2’s 32 rows are encoded in parallel by a 32-channel ADC ASIC, OWB-1. The custom daughter board with the hybrid detector is placed in a thermally controlled vacuum chamber for a moderate cooling. This paper will present the characterization tests of the ASIC, the dedicated test set-up and the first spectroscopic measurements of the MC2-1K hybrid detector.

An Average Model of DC–DC Step-Up Converter Considering Switching Losses and Parasitic Elements

Power electronic converters represent a pillar of modern power systems, especially since generation from renewable energy sources, such as photovoltaics, have been introduced. One of their main characteristics consists of the high flexibility in converting different voltage levels and waveforms. As for all the conversion devices, they are subjected to unavoidable losses introduced by non-ideal components. For this reason, in the last few decades numerous research activities have been devoted to model their behavior and predicting the global efficiency. In spite of the number of scientific publications on the topic, the non-idealities have been rarely studied in terms of their impact on the input-output characteristics of the converter. In this paper, the conventional equivalent circuit of a step-up DC/DC converter has been upgraded in order to introduce the effects of both conduction and switching losses. The obtained formulation, applicable to all DC/DC converters, allows a more accurate average model that is particularly suitable for the study of multi-converter architectures, as for the most recent renewable energy sources applications. Finally, thanks to a dedicated test setup, the results of an experimental campaign demonstrate how the new formulation faithfully predicts its electrical behavior.

Influence of vacuum and its degradation on the sensing element of the Coriolis Vibratory Gyroscope

Coriolis Vibratory Gyroscope (CVG) is an inertial rotation rate measurement sensor for inertial navigation applications. The rotation sensitive element is a hemispherical vibrating resonator, made of fused silica. It is forced to vibrate at a particular resonant mode with electrostatic forcing. As the resonator is a glass material its vibration amplitude is limited to the submicron level. An ultra-high vacuum environment is necessary for the resonator to sustain the vibration amplitude. Securing the required vacuum level is critical in sensor development. A detailed analysis has been carried out on the damping forces present at various ambiance conditions, the need for threshold vacuum level, threshold forcing voltage for the resonator, and different ways of degradation of the vacuum level in the sensor capsule. This paper presents an experimental study on the damping forces that appear on the resonator by measuring the Q factor at various vacuum levels, vacuum leak rate through weld joints, securing the vacuum environment, and remedial action to arrest vacuum in the sensor volume. Dedicated test setups have been established to carry out the experimental research work.

Design, manufacture and test of a low-cost solar cooker with high-performance light-concentrating lens

Solar radiation can be considered as one of the most suitable energy source to be used for cooking food. It is therefore important to promote advancement in solar cooking systems, in particular as concerns their efficiency and cooking times. In this work, we designed, realized and tested a novel low-cost solar cooker that uses a high-performance light-concentrating Fresnel lens, which is able to concentrate onto a small focal area a large amount of solar radiation. The radiation is then reflected by a mirror towards a cooking surface, where a pot can be located. The cooker has a geometrical concentration ratio of 40.97. In order to characterize the thermal performance of the cooker, we carried out several outdoor tests with a dedicated test setup, using water and silicone oil as absorbing media. Respect to other solar cookers, results show that the proposed cooker is able to reach high temperatures with good efficiency and reduced heating times: 3 kg of water can reach 90 °C in around 30 min, while 3 kg of silicone oil can be taken from 40 to 170 °C in less than one hour.

Active Control of Combustion Noise by a Twin Resonator Trim Adjustment System

ABSTRACT Variable volume Helmholtz resonator systems offer an advantage for trim adjustment active control in liquid rocket engines due to the low bandwidth requirement on the actuator. In the present work, a trim adjustment active control system based on twin variable volume Helmholtz resonators is investigated experimentally in open loop on a dedicated test setup. It is found that the twin variable resonators can control combustion noise in open loop in a methane-air combustion chamber. The frequency at which acoustic absorption is optimum deviates significantly from the fundamental system frequency at some of the equivalence ratios studied. This happens when the correlation for impedance available in the published literature is used as such. In this work, the impedance characteristics were derived directly from the measurements. It is demonstrated from the impedance characteristics that the twin resonator system is able to achieve consistently better performance than a single resonator over a range of equivalence ratios. It is concluded that the twin resonator system concept stands validated in open loop for combustion noise. A practical scheme for implementing a twin resonator active control system in open loop is outlined. The results indicate that twin resonators should be further investigated for closed loop suppression of thermoacoustic instability.

A Cost-Effective Electro-Hydraulic Actuator Solution with Open Circuit Architecture

With the recent electrification trend in the fluid power area, more research has been incentivized to propose cost-effective and energy-efficient solutions for hydraulic systems. Hence, electro-hydraulic actuator (EHA) architectures receive increasing attention. The paper proposes a novel open-circuit EHA architecture, with the goal to obtain a cost-effective solution for mobile applications while maximizing the overall system efficiency. The proposed EHA is capable of meeting or exceeding traditional off-road machine performance, therefore enabling further electrification of off-road machines. Four-quadrant functionality, covering the full speed range, is achieved by a combination of a variable electro-hydraulic drive and valves with different functions. Focusing on the steady-state performance, the functionality is validated by numerical as well as experimental methods. A simulation model based on the Amesim environment and a dedicated test setup was developed to verify the performance. The good match between simulation and experimental results confirms the potential of the formulation approach of the proposed EHA for applications with different duty cycles and power levels.

Unmanned Aircraft Systems Performance in a Climate-Controlled Laboratory

Despite many research studies focus on strategies to improve autopilot capabilities and bring artificial intelligence onboard Unmanned Aircraft Systems (UAS), there are still few experimental activities related to these vehicle performance under unconventional weather conditions. Air temperature and altitudes directly affect thrust and power coefficients of small scale propeller for UAS applications. Reynolds numbers are usually within the range 10,000 to 100,000 and important aerodynamic effects, such as the laminar separation bubbles, occur with a negative impact on propulsion performance. The development of autonomous UAS platforms to reduce pilot work-load and allow Beyond Visual Line of Sight (BVLOS) operations requires experimental data to validate capabilities of these innovative vehicles. High quality data are needed for a deep understanding of limitations and opportunities of UAS under unconventional flight conditions. The primary objective of this article is to present the characterization of a propeller and a quadrotor capabilities in a pressure-climate-controlled chamber. Mechanical and electrical data are measured with a dedicated test setup over a wide range of temperatures and altitudes. Test results are presented in terms of thrust and power coefficient trends. The experimental data shows low Reynolds numbers are responsible for degraded thrust performance. Moreover, details on brushless motor capabilities are also discussed considering different temperature and pressure conditions. The experimental data collected in the test campaign will be leveraged to improve UAS design, propulsion system modelling as well as to provide guidelines for safe UAS operations in extreme environments.

Effects of saturation temperature on the boiling properties of carbon dioxide in small diameter pipes at low vapour quality: Heat transfer coefficient

The renewed interest in carbon dioxide as a refrigerant stems from both the environmental friendly properties of this fluid and from its extremely favourable performance as compared to most standard refrigerants at the same temperature, in particular for all applications where small size evaporators are required. Since a dependable forecast of heat transfer is crucial for these applications and reliable predictive methods spanning a large temperature range are so far missing, a long-term study has been launched to create a consistent and reliable experimental database studying the peculiarities of boiling carbon dioxide in mini- and micro-channels, aiming at a future improvement of predictive models. This study presents results on the local heat transfer coefficient of boiling carbon dioxide at low vapour quality (0 < x < 0.4) in 200 mm-long stainless steel tubes with inner diameters of 2.15 mm, 1 mm and 0.5 mm. The dedicated test setup equipped with high precision sensors allows to probe a wide range of saturation temperatures (+15∘C to -25∘C) and mass fluxes between 100 and 1800 kg/m2s have been studied under diabatic test conditions for heat fluxes from 5 to 35 kW/m2. The results discussed focus on the influence of the saturation temperature on the two-phase heat transfer coefficient. It is suggested that the combination of shifting physical properties of carbon dioxide and different flow confinement conditions cause a change in the phenomenological behaviour of the flow and that a transition between macro- and micro-scale most likely occurs within the range of tested parameters. Furthermore it is found that a shift in the applicability of existing prediction methods is caused by those effects and no correlation is able to predict the experimental data and trends in the whole temperature range observed. However, a critical performance analysis of selected correlations provides useful hints on the variation of the phenomenological flow boiling features induced by the combined effects of changing saturation temperature and evaporator diameter.

Characterization of novel ceramic composites for rocket nozzles in high-temperature harsh environments

This paper presents the results of experimental tests for the characterization of Ultra-High-Temperature Ceramic Matrix Composite (UHTCMC) materials for near-zero erosion rocket nozzles. Two dedicated test set-ups were developed for preliminary screening of material candidates in a representative environment, characterized by relevant heat flux and temperature. The experimental set-up was based on a lab-scale 200N-class hybrid rocket engine, employing gaseous oxygen as the oxidizer and High-Density PolyEthylene as fuel; the configurations included free-jet test, in which small button-like samples were exposed to the supersonic exhaust jet of the rocket nozzle; and chamber inserts, in the shape and size of an annular element, placed inside the rocket combustion chamber. Computational Fluid Dynamic simulations, for modeling heat transfer and combustion chemical reactions, complemented the experimental observations and supported the characterization of test conditions. Samples with ZrB2-SiC matrix and continuous or chopped carbon fibers, sintered by either Hot Pressing or Spark Plasma Sintering were tested. Free-jet test samples demonstrated a substantially improved erosion resistance with respect to conventional graphite and in one case a negligible material recession. UHTCMC samples erosion was associated to the occurrence of a rapid rise in surface temperature, which achieved values over 2900 K. Chamber inserts, besides confirming the outstanding erosion resistance of UHTCMCs with respect to traditional materials (i.e. C/SiC), proved that long-fibers samples with sufficient porosity are more likely to withstand thermal shocks typical of the rocket combustion environment.

Effects of saturation temperature on the boiling properties of carbon dioxide in small diameter pipes at low vapour quality: Pressure drop

The thermal management of most of the silicon pixel detectors at the heart of the Large Hadron Collider experiments at CERN relies on boiling carbon dioxide inside compact heat exchangers of small hydraulic diameter at saturation temperatures between +15 ∘C and −30 ∘C. Due to the current lack of suitable predictive models, a long-term study has been launched to create a consistent and reliable experimental database studying the peculiarities of boiling carbon dioxide in mini- and micro-channels. This study presents results on the total pressure drop of boiling carbon dioxide at low vapour quality (0 < x < 0.4) in 200 mm-long stainless steel tubes with an inner diameter of 2.15 mm, 1 mm and 0.5 mm. By means of a dedicated test setup equipped with high precision sensors, a wide range of saturation temperatures (+15 ∘C to −25 ∘C) and mass fluxes (100 to 1800 kg/m2s) have been explored and diabatic tests were carried out for heat fluxes from 5 to 35 kW/m2. The data presented focus on the influence of the saturation temperature on the two-phase pressure drop. It is suggested that the combination of shifting physical properties of carbon dioxide and different confinement conditions causes a change in the phenomenological behaviour of the flow and that a transition between macro- and micro-scale most likely occurs within the range of test parameters. It is further shown that a shift in the applicability of existing prediction methods is caused by those effects and no correlation is able to predict the experimental data and trends in the whole temperature range. A selective approach to the use of existing correlations is also proposed.

Frictional Characteristics of Brake Pad Materials Alternate to Asbestos

Nevertheless, asbestos though having ample physical and tribo-mechanical properties is being banned worldwide due to its health hazardousness. Most importantly, any material replacing asbestos should have comparable friction properties. This paper aims at comparative study of frictional characteristics of asbestos base and asbestos free brake pad materials. A total of three friction materials namely AF-22 (metallic based), CL-3003 (fine brass based) and DM-6 (asbestos based) were compressed and moulded into a sample. Experiments were performed using dedicated test set-up based on Pin-on-disc principle. Coefficient of friction was compared for three materials at different conditions of sliding velocity and pressure. Experiments were performed using Taguchi’s L27 orthogonal array. Ranking of the parameters have been done based on experimental results and S/N ratio analysis. The elemental composition of materials was measured by EDS technique. Scanning electron micrographs of brake pad samples were tested at different magnifications. Further investigations to evaluate wear rate, stopping distance under simulative test conditions are suggested.

Integrated, Multichannel Readout Circuit Based on Chopper Amplifier Concept for FET-Based THz Detectors

This work presents the integrated, multichannel readout circuit dedicated to FET-based THz detectors. Described solution provides an unique approach to FET detectors readout, able to replace the measurement equipment deploying the lock-in technique and to eliminate the necessity of modulating the THz wave. The IC proposed by the authors is based on the chopper amplifier architecture, enhanced and adapted for multichannel signal processing. It also ensures significant 1/f noise minimisation, which is the key requirement for the FET-based detectors readout. The circuit prototypes were manufactured in standard 350 nm CMOS process (AMS A.G.) and then measured in the dedicated test set-up.

Experimental Investigation of Shaft Radial Load Effect on Bearing Fault Signatures Detection

This paper investigates the influence of external radial load applied to the shaft on bearing fault detection based on vibration or current in induction motors operating under different conditions. This paper details the results of a laboratory trial comprising different test sets on the condition monitoring and fault diagnostic of a six-poles induction motor using a design of experiment (DOE) approach. The dedicated test setup comprises a custom-made fixture that allows us to dynamically vary the radial load applied to the output shaft. The aim is to investigate the effects of radial load on the fault diagnosis of shaft bearings and the interactions between other operating parameters, such as output torque. Specific scalar parameters have been proposed for the condition monitoring of the test motor from vibration and current data. The correct choice of the significant parameters is proven by the strong dependence on the damage returned by DOE results.

Improved Friction Joint With Self-Locking Grips

Flexible risers are used in the oil industry to transport liquids and gas from the seafloor to extraction and production equipment at the sea surface. Ongoing research aims at using composite materials instead of steel, in order to reduce weight and increase stiffness. Ensuring an optimal load transfer between the composite and metal components is very important. This paper presents an improved method for anchoring a flat fiber-reinforced tendon using a double grip system with self-locking grips. The novelty is the combination of new experimental results and finite element (FE) analysis to develop a superior dry friction grip. Experimental results are carried using a dedicated test setup, through which the test parameters can be accurately controlled. The efficiency of the grip system during pullout is superior to results obtained with flat grips. Numerical results offer an in-depth understanding of the influence between friction, geometrical parameters, and performance, making it possible to optimize the design. Results show that this grip system offers immediate technical applications, in a variety of conditions.