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We present an electric power meter that capitalizes on the interaction of electrothermal strain and mechanical vibration in a micro-electro-mechanical systems (MEMS) beam undergoing the antisymmetric mode of vibration. This is achieved by using a resonant bridge driven with an electrothermal modulation technique. The change in electrical power is monitored through the alteration in the mechanical stiffness of the structure, which is tracked electrostatically. The observed deflection profile of the beam under the influence of electrothermal effects shows that the deflection geometry due to buckling exhibits similar trends as the first symmetric vibrational mode, in contrast to the antisymmetric mode. Therefore, we compare two distinct vibrational modes, converting the compressive thermal stress generated by the input electrical power via Joule heating into a shift in the resonance frequency. By employing antisymmetric vibrational mode, the output of our device is consistently monotonic to the input electrical power, even when the microbeam is experiencing buckling deflections. In addition, the sensing operation based on antisymmetric modes yields only a 1.5% nonlinear error in the response curve, which is ten times lower than that of symmetric modes. The observed deformation shape of the resonator agrees with the results obtained from multi-physics finite simulations. Finally, this approach has the potential to be extended to other frequency-shift-based sensors, allowing for higher linearity. [ABSTRACT FROM AUTHOR]

Hydrogen rotary engines are promising power sources for the future hydrogen society, and improving their thermal efficiency helps propel tomorrow's car farther. This research looked into the combustion process to reduce fuel consumption. Primary studies of combustion duration and location showed that increasing the local mass burning rate in the L-side of the combustion chamber by generating turbulence was beneficial. Experiments with optical and real rotary engines proved that turbulence effectively increased mass burning rate in L-side and consequently engine's thermal efficiency and its lean limit.

Petrological, geochemical, and biostratigraphical investigations have been conducted on seventy-nine samples from four selected sections in Jordan to understand the factors that influenced the enrichment and deposition of massive phosphorite deposits. The calcareous nannofossil marker species Broisonia parca constrica and Reticulofenestra bisecta, from the assigned sections 1 and 2 (Hawar and Al Dhahikiyya), were indicative of the Campanian and Eocene periods, respectively. The enrichment of some ecological marker species such as Kamptnerius magnificus indicates that there were cold periods during phosphate precipitation. All thin sections of the phosphate samples are of grainstone and packstone textures and are composed of skeletal fragments and peloids. Skeletal fragments appeared to be the main component of Hawar phosphates with the existence of peloids, while peloids were the component in sections 2 and 3 (section 3: Al Hisa). At least three intervals of high phosphorous values appeared in the Hawar section, showing variations in the Ca and Nd isotopes and in the terrigenous inputs. Four periods of phosphate enrichment are observed in Sections 2 and 3. These are deep water circulation periods of the early and late Campanian period, interrupted by two periods of submarine and continental weathering. Deep water circulation was initiated during cooling in the Campanian period and indicated by high phosphorous and Ca isotope components and a decline in terrigenous indicators (Al, Si, Ti, and Fe). Submarine weathering during warmer deep-sea periods is indicated by a rising Nd isotope ratio when many of the igneous provinces were subjected to weathering. Continental weathering took place in the warmer periods, with the hydrologic cycle and enhancement of terrigenous indicators (Al, Si, Ti, and Fe) being observed. The effect of the hydrologic cycle was at its highest in the south during the Campanian period and in the Eocene, as both represented shallower settings. [ABSTRACT FROM AUTHOR]

Terracing and the construction of a flood control system in Petra has allowed a unique opportunity to examine landscape conditions and changes beginning with the Late Iron Age. The study area is the Hremiyyeh catchment that flows into the core of the archaeological city of Petra and therefore constitutes an important key to understanding the human settlement of the area. The location was chosen as a focal point for intensive investigation and the study of human response to environmental change. This study involved careful documentation of the topography, geology, and archaeology of the site. In addition, samples were taken for the dating of terrace construction and changes in the landscape. The study indicates that the hydrological interventions began in the Late Iron Age, and intensified during the Nabataean and Early Roman periods. At the time, some of the drainage areas were already deeply gullied, while other parts had recently accumulated sediments. The lower terraces became filled with water-logged sediments, leading to the deposition of carbonates. The upper terraces changed the drainage pattern and deposition of the sediments. The sediments trapped there seem to have been less waterlogged. The abandonment of the system at the end of the Byzantine to Early Islamic periods led to partial collapses, gullying, and bedrock downcutting. Due to soil accumulation, the upper terraces were restored and enhanced with new ones around the 11th. Century CE, probably due to partial reclamation of the area by nomadic settlers, with charred botanical evidence found indicating the burning of wild vegetation in favor of domesticated cereal and legumes, with relatively humid conditions. [ABSTRACT FROM AUTHOR]

A project to restore the function of an ancient Nabatean flood control system that had previously protected the Plaza of the Treasury (Al-Khazna), Petra, is described herein. The project involves a large, multidisciplinary team, numerous stakeholders, and a difficult setting. It involves training, outreach, documentation, archaeological investigation, hydrological modeling, architectural conservation and rehabilitation. Previous studies had indicated that such flood control systems operate by controlling water flow from the headwaters in order to prevent sudden surges of water. Since Petra often suffers from the effects of flash floods, the Petra Development and Tourism Regional Authority (PDTRA) asked the researchers to explore the possibility of controlling modern-day floods using these systems. This culminated in the partial rebuilding of the flood control system and important lessons on their limitations and how they work. [ABSTRACT FROM AUTHOR]

Microresonator-based temperature sensors offer stable and high-resolution temperature detection. However, typical temperature-sensing techniques based on resonators suffer from design complexity and low sensitivity. In this study, we present a simple high-sensitivity temperature sensor that comprises a sealed electrostatically actuated clamped–clamped silicon microbeam resonator. The sensor’s high sensitivity is attributed to the thermal-strain effects due to the mismatch between the thermal expansion coefficients of the composite materials. And the sensitivity is further enhanced by operating the resonator near the buckling zone via in situ Joule heating. In addition, The sensor operates at a single drive frequency that corresponds to the resonant frequency at the maximum temperature. A change in temperature induces a thermal strain that shifts the resonant frequency, which changes the output voltage. This considerably simplifies the readout system from the typical frequency-tracking method to the proposed amplitude tracking method. The encapsulated sensor achieves a minimum detectable temperature of 0.0196 °C and an absolute temperature coefficient of frequency of 1757 ppm/°C. These results demonstrate the great potential of the proposed sensor for efficient resonant thermal sensing with high resolution, enhanced sensitivity and a simplified readout scheme. [ABSTRACT FROM AUTHOR]

This paper aims to examine the provenance of Roman marble statues uncovered from the Eastern Roman Baths (Gerasa of the Decapolis, Jordan) during the 2016 and 2017 excavation campaigns. The samples were characterized using magnifying lenses, an x-ray diffractometer, a stable isotope mass spectrometer, and a polarized light microscope. The results show that the Aphrodite and drapery marbles are dolomitic and most probably from the Cape Vathy of Thassos Island (Greece); the Asklepios and Zeus marbles are fine-grained and most probably from Docimium (Turkey); the Melopmene, Demetrius Aphrodite, and eagle marbles are fine-grained and most probably from Penteli (Greece); the dancing satyr and Apollo marbles are coarse-grained and most probably from Lakkos (Paros Island, Greece); and the marble fragments of unknown statues are coarse-grained and most probably from Marmara (Proconnesus-1) Island, Turkey. The results indicate that sculptors preferred fine white marbles for carving sculptures in spite of their source, price, and sculpture workshop. The results agree with previous studies that showed a wide variety of marble sources, indicating that Gerasa prospered in its location on the King's Highway and participated in a well-established trade network with the major cities and marble sources in the Roman Empire. [ABSTRACT FROM AUTHOR]

We present a novel design of a low-power micro-electro-mechanical digital to analog converter (DAC) based on a clamped-clamped micro-beam resonator with multiple split electrodes and capacitive airgaps of various widths. The proposed n-bit DAC device operates at a single drive frequency and can access one of $2^{\mathbf {n}}$ distinct stable states based on the applied digital combination. The digital inputs (binary numbers) modulate the beam resonance frequency using the electrostatic softening effect, where the larger binary numbers result in higher beam resonance frequency. Although the tested device consumes 151 pJ per conversion step with a conversion rate of 0.64 kHz, we show that by moderate downscaling of the device dimensions, femto-joules energy consumption and MHz conversion rates are attainable. [2019-0264] [ABSTRACT FROM AUTHOR]

We report a new gas sensing technique based on the simultaneous tracking of multiple modes of vibration of an electrothermally heated bridge resonator operated near the buckling point. The proposed technique maximizes the sensitivity of the sensor to changes in gases concentrations. We demonstrate a 200% frequency shift in contrast to 0.5% resistance change using the conventional resistive technique. The method also demonstrates selective identification for some gases without the need for surface functionalization of the microstructure. The proposed method is simple in principle and design and is promising for achieving practical low-cost gas sensors. [ABSTRACT FROM AUTHOR]

We investigate, experimentally and theoretically, the linear mode coupling between the first symmetric and antisymmetric modes of an electrothermally tuned and electrostatically actuated micromachined arch resonator. The arch is excited using an antisymmetric partial electrode to activate both modes of vibrations. Theoretically, we explore the static and dynamic behavior using the Galerkin method. When tuning the electrothermal voltage, the first symmetric frequency increases while the first antisymmetric frequency decreases until they cross. The results show linear coupling and hybridization of both modes near crossing only in the presence of the perturbation from the electrostatic force using the partial electrode. We show the linear merging of both modes at crossing. Also, the eigenfrequency variation around crossing shows a ratio of 2:1 between the second symmetric mode and the first symmetric/antisymmetric modes, which can lead to simultaneous 1:1 and 2:1 internal resonances. [ABSTRACT FROM AUTHOR]

In this brief, the design principles and experimental demonstration of a compact full adder along with a reprogrammable 4-input logic gate are presented. The proposed solution for implementation of digital circuits is based on a clamped–clamped micro-beam resonator with multiple split electrodes, in which the logic inputs tune the resonance frequency of the beam. This technique enables re-programmability during operation, and reduces the complexity of the digital logic design significantly; as an example, for a 64-bit adder, only 128 micro-resonators are required, compared to more than 1500 transistors for standard complementary metal–oxide–semiconductor (CMOS) architectures. We also show that an optimized simulated micro-resonator-based full adder is 45 times smaller than a CMOS mirror adder in 65-nm technology. While the energy consumption of this early generation of micro-resonator logic gates is higher than the CMOS solutions, we show that by careful device optimization and shrinking of the dimensions, femtojoules energy consumption and MHz operation, required by Internet of Things applications, are attainable. [ABSTRACT FROM AUTHOR]

Groundwater resources in semi-arid climates in countries like Jordan have experienced deterioration both in quantity and quality. This paper aims at locating potential groundwater recharge areas in the Upper Yarmouk River Basin (UYRB) using weighted overlay method in ArcGIS. The input data for this analysis included geology, soil, land use/land cover, slope, lineament density, and drainage density. The results classified the study area in terms of its water infiltration potential into five categories, in which zones of high and very high infiltration potential represented 36 % of the investigated area. The maximum infiltration potential dominated the north, east, and southwest parts of the study. This is most probably due to the major influence of soil types, land cover and lineaments in the southwest, and the increased role of drainage density and topography in the north and eastern parts. The water infiltration potential was successfully validated using data from rainfall simulations and Vertical Electrical Soundings, suggesting that the moisture content of the upper 10m of the soil column is within the range 33-48%. The adopted model can be seen as a guide for water resources security and protection. [ABSTRACT FROM AUTHOR]

Jordan has huge organic-rich oil shale resources. The exploitation of this resource for generating electrical power by direct combustion is eminent. This process will produce huge ash tailings that contain high concentrations of potentially leachable toxic elements (e.g. Cr+6, V+5, As+3, Cd+2). This ash is friable and eventually will interact with rainwater, forming a leachate rich in toxic elements that might reach soil, plants and surface and groundwater resources. Therefore, as a preventive measure, the current study analyzed the mobility of toxic elements in the ash of burned oil shale (BOS), in particular Cr+6, and aimed to fix them through mixing with other natural locally available materials such as phosphogypsum (PG) and red soil (RS). In addition, a study of the changes in mineralogy, petrography and engineering properties with time during a period of up to 12 months was conducted. The ageing results revealed that the ash + RS mixtures showed a lower leachability of toxic elements in the pH range of 5-9 in comparison with other mixtures. Besides, the said mixtures exhibited an increase in the values of unconfined compressive strength (UCS) and decrease in those of permeability (PE) unlike other mixtures. Moreover, ettringite and portlandite phases increasingly appeared in these mixtures with time, which explains the increase of UCS. The USC of the ash alone mixture was the second lowest and that of the ash + PG mixture the lowest. Therefore, mixing the produced ash with RS (3:1 ratio) under water saturation conditions would afford the best long-term solidification of harmful toxic elements. [ABSTRACT FROM AUTHOR]

Most gas sensors suffer from the cross sensitivity to environmental temperature, which significantly reduces the accuracy and reliability of measurements. Current solutions require the fabrication of a thermometer in close proximity to the gas sensor or an identical reference sensor to compensate for the sensor drift due to temperature. This increases the device size, fabrication cost, and the power required to operate the sensor; and also adds to the complexity of the device circuit for signal processing. Here, we demonstrate a single resonant gas sensor, based on a microbeam uniformly coated with metal-organic frameworks (MOFs), capable of simultaneously measuring environmental temperature and gas concentration (water vapor). Using the electrostatic harmonic voltage, we actuate the microbeam simultaneously near the first and second vibration modes. The frequency shifts of these two modes due to physical stimuli changes are monitored in real time. The lower electrode of the clamped-clamped microbeam resonator is perforated to reduce the effect of squeeze film damping, thereby allowing operation under atmospheric pressure. We demonstrate experimentally the effectiveness of this technique to measure the environmental temperature and gas concentration. Based on the theoretical analysis and the Allan deviation results, a minimum detectable temperature of 0.03 °C and water vapor concentration of 4.6 ppm is demonstrated. [ABSTRACT FROM AUTHOR]

We demonstrate a resonant gas sensor uniformly coated with a metal-organic framework (MOF) and excited near the second vibration mode for enhanced sensitivity. The possibility of realizing a smart switch triggered upon exceeding a threshold mass is demonstrated when operating the resonator near the dynamic pull-in instability. The resonator is based on an electrostatically excited clamped–clamped microbeam. The microbeam is fabricated from a polyimide layer coated from top with Cr/Au and from bottom with Cr/Au/Cr layer. The geometry of the resonator is optimized to reduce the effect of squeeze film damping, thereby allowing operation under atmospheric pressure. The electrostatic electrode is designed to enhance the excitation of the second mode of vibration with the minimum power required. Significant frequency shift in kilohertz is demonstrated for the first time upon water, acetone, and ethanol vapor exposure due to the MOF functionalization and the higher order mode excitation. The adsorption dynamics and MOF selectivity are investigated by studying the decaying time constants of the response upon gas exposure. [2017–0218] [ABSTRACT FROM PUBLISHER]

We present multi-function microelectromechanical systems (MEMS) logic device that can perform the fundamental logic gate AND, OR, universal logic gates NAND, NOR, and a tristate logic gate using mixed-frequency excitation. The concept is based on exciting combination resonances due to the mixing of two or more input signals. The device vibrates at two steady states: a high state when the combination resonance is activated and a low state when no resonance is activated. These vibration states are assigned to logical value 1 or 0 to realize the logic gates. Using ac signals to drive the resonator and to execute the logic inputs unifies the input and output wave forms of the logic device, thereby opening the possibility for cascading among logic devices. We found that the energy consumption per cycle of the proposed logic resonator is higher than those of existing technologies. Hence, integration of such logic devices to build complex computational system needs to take into consideration lowering the total energy consumption. [2017-0041] [ABSTRACT FROM AUTHOR]

This work aims to investigate theoretically and experimentally various nonlinear dynamic behaviors of a doubly clamped microbeam near its primary resonance. Mainly, we investigate the transition behavior from hardening, mixed, and then softening behavior. We show in a single frequency-response curve, under a constant voltage load, the transition from hardening to softening behavior demonstrating the dominance of the quadratic electrostatic nonlinearity over the cubic geometric nonlinearity of the beam as the motion amplitudes becomes large, which may lead eventually to dynamic pull-in. The microbeam is fabricated using polyimide as a structural layer coated with nickel from top and chromium and gold layers from the bottom. Frequency sweep tests are conducted for different values of direct current (DC) bias revealing hardening, mixed, and softening behavior of the microbeam. A multimode Galerkin model combined with a shooting technique are implemented to generate the frequency-response curves and to analyze the stability of the periodic motions using the Floquet theory. The simulated curves show a good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

We present an H-shaped resonator made of two clamped–clamped microbeams mechanically coupled at the middle with a strong coupler to achieve, in a single device, mechanical amplification of the response signal, filtering, and frequency conversion simultaneously. Usingmechanicalamplification combinedwith combination resonances generated from a mixed-frequency excitation, a wideband tunable filter, and a simultaneous frequency up and down convertors at multiple bands is demonstrated. The proposed coupled structure, when combined with the easy-to-implement technique of frequency mixing, is promising for applications in an RF chain. [ABSTRACT FROM PUBLISHER]

Amplifying the signal-to-noise ratio of resonant sensors is vital toward the effort to miniaturize devices into the sub-micro and nano regimes. In this paper, we demonstrate theoretically and experimentally, amplification through mechanically coupled microbeams. The device is composed of two identical clamped-clamped beams, made of polyimide, connected at their middle through a third beam, which acts as a mechanical coupler. Each of the clamped–clamped microbeams and the coupler are designed to be actuated separately, hence providing various possibilities of actuation and sensing. The coupled resonator is driven into resonance near its first resonance mode and its dynamic behavior is explored via frequency sweeps. The results show significant amplification in the resonator amplitude when the signal is measured at the midpoint of the coupler compared with the response of the individual uncoupled beams. The static pull-in characteristics of the resonator are also studied. It is shown that the compliant mechanical coupler can serve as a low-power radio frequency switch actuated at low voltage loads. [2016-0100] [ABSTRACT FROM AUTHOR]

Quartz crystal microbalance (QCM) coated with poly-4-vinylpyridine (PVP) and metal organic framework HKUST-1 are investigated and compared for humidity sensing. Drop casting method is employed to coat the PVP and HKUST-1 solutions onto the surface of a quartz crystal microbalance. The resonance frequencies of these sensors with varying relative humidity (RH) from 22% RH to 69% RH are measured using impedance analysis method. The sensitivity, humidity hysteresis, response, and recovery times of these sensors are studied. The sensitivities of uncoated, PVP, and HKUST-1 coated QCM sensors are 7 Hz, 48 Hz, and 720 Hz, respectively, in the range of 22% RH–69% RH. The extraction of desorption rate and adsorption energy associated with the adsorption and desorption of water molecules on these surfaces reveals that HKUST-1 has better sensing properties than PVP and uncoated QCM sensors. In this work, the HKUST-1 coated QCM is shown to be a promising material for moisture detection. [ABSTRACT FROM AUTHOR]

There is an increasing interest to realize smarter sensors and actuators that can deliver a multitude of sophisticated functionalities while being compact in size and of low cost. We report here combining both sensing and actuation on the same device based on a single microstructure. Specifically, we demonstrate a smart resonant gas (mass) sensor, which in addition to being capable of quantifying the amount of absorbed gas, can be autonomously triggered as an electrical switch upon exceeding a preset threshold of absorbed gas. Toward this, an electrostatically actuated polymer microbeam is fabricated and is then functionalized with a metal-organic framework, namely, HKUST-1. The microbeam is demonstrated to absorb vapors up to a certain threshold, after which is shown to collapse through the dynamic pull-in instability. Upon pull-in, the microstructure can be made to act as an electrical switch to achieve desirable actions, such as alarming. [ABSTRACT FROM AUTHOR]

The objective of this paper is to demonstrate the integration of a MOF thin film on electrostatically actuated microstructures to realize a switch triggered by gas and a sensing algorithm based on amplitude tracking. The devices are based on the nonlinear response of micromachined clamped-clamped beams. The microbeams are coated with a metal-organic framework (MOF), namely HKUST-1, to achieve high sensitivity. The softening and hardening nonlinear behaviors of the microbeams are exploited to demonstrate the ideas. For gas sensing, an amplitude-based tracking algorithm is developed to quantify the captured quantity of gas. Then, a MEMS switch triggered by gas using the nonlinear response of the microbeam is demonstrated. Noise analysis is conducted, which shows that the switch has high stability against thermal noise. The proposed switch is promising for delivering binary sensing information, and also can be used directly to activate useful functionalities, such as alarming. [ABSTRACT FROM AUTHOR]