Top PDF Thermal Flow Sensors for Harsh Environments

Thermal Flow Sensors for Harsh Environments

Thermal Flow Sensors for Harsh Environments

In the late 1990’s, mounting technology with small dimensions were not available for commercial silicon based sensor. Thick film technology was more common for thermal sensors along with packaging. For instance, Dyrbye et al. proposed a packaging technique, where the ceramic substrate holds a thin insulating membrane. The nickel sensor encapsulated by a glass layer of 6 μm , Figure 13(a). Stainless steel of 100μm thickness is glued to the sensing element for protection and provides a stable and short thermal path to the aggressive media. The packaged sensor was able to detect a frequency of 0.05-33Hz when tested with water flow[125]. However, this packaging suggested the inadequacy of chemical stability and the lack of maturity of the packaging schemes at that time. This outcome led to the development of various packaging approaches, some of those are discussed below.
Show more

32 Read more

Autonomous robots for harsh environments : a holistic overview of current solutions and ongoing challenges

Autonomous robots for harsh environments : a holistic overview of current solutions and ongoing challenges

(DuBose, 2017; Gómez & Green, 2017). In the case of outdoor deployment, drones can be used to inspect tanks, pipelines and refineries as a whole, as demonstrated by English (2015) and Shukla, Xiaoqian, & Karki (2016). These robots are either manually controlled or flown in semi-autonomous mode, with an operator providing high-level commands from a ground control station. As such, these systems rely heavily upon robust flight control techniques consisting of dead reckoning, inertial navigation, data fusion and tracking control. Furthermore, UAVs are effective for the exploration of oil and gas fields located in more remote and harsh environments not suitable for human exploration. Conversely, single UAV systems have been developed for the purpose of reliable internal (sub)-surface inspections of pressure vessels, tanks and other interior features. One notable commercial development is the Elios UAV, developed by Flyability (Knukkel, 2017). This system is surrounded by a spherical cage that protects the system from collision and enables the UAV to roll along surfaces when moving in cluttered environments. By carrying an on-board thermal camera, lighting and optical camera operators can remotely control the system from a safe environment, allowing the inspection of internal environments to be performed in minimal time. From the perspective of health and safety, this drastically saves cost and downtime as it eliminates the need to prepare the inspection space for human entry.
Show more

21 Read more

Characterization of Fiber Bragg Gratings as Thermal Sensors in Complex Environments.

Characterization of Fiber Bragg Gratings as Thermal Sensors in Complex Environments.

The FBG arrays behave as expected. The lower maximum temperature in the second test is due to the lower flame load applied by the burner, though the total time the flame load was applied to the specimen was longer than in the first test. The response of the horizontal array is tightly bound within 1 o C. Any discrepancies within the horizontal data are due to the horizontal track not being perfectly horizontal, non-uniformities of the flame, material defects within the TPS block and transverse heat flow. The results from the diagonal array are also tightly bound, though the difference between the lowest and highest recorded temperature is significantly more noticeable than the horizontal array. Even though the array is diagonally embedded within the specimen, due to the angle of the embedding (26.6 o ) and the spacing of the FBGs in the array (2.5 mm between the center of adjacent FBGs), the FBGs are vertically very similar, with only a 1.12 mm height difference between the centers of adjacent FBGs. To highlight the response of the diagonal array, Figs. 5.33 and 5.34 show the response of the diagonal array in the individual tests without the thermocouple data overlaid on the FBG response or the response of the horizontal array. The drop in recorded temperature after 1500 seconds is due to the burner being extinguished. Even though the door between the burner and the specimen was closed, there was still heat flow through the specimen.
Show more

241 Read more

A detailed characterization of BaMgAl10O17:Eu phosphor as a thermal history sensor for harsh environments<sub/>

A detailed characterization of BaMgAl10O17:Eu phosphor as a thermal history sensor for harsh environments<sub/>

An alternative off-line method based on the use of thermographic phosphors was has been devised by Feist et al. [8]. Thermographic phosphor materials usually consist of a ceramic host and a rare-earth dopant that emit luminescence upon excitation by a UV or visible light source. They have been studied for many years as on-line temperature sensors [9-13] with applications on surfaces [14-17] and for gas flow temperature measurements [18-21]. Off-line measurements using thermographic phosphors are based on irreversible changes in their optical properties caused by the exposure to high temperatures and oxidising environments. These optical properties can be measured using the same methods as on- line thermographic phosphors, such as the lifetime decay and intensity ratio methods widely described in the literature [9, 13]. Thermographic phosphors present some advantages when compared to thermal paints: the measurement is objective and unaffected by errors due to visual interpretation, temperature data is continuous and therefore resolution is improved, in-situ measurements can be made more easily which can remove the need to dismantle the engine and the chemicals used are not restricted by REACH regulations.
Show more

23 Read more

A methodology for design of lightweight robotic arm links in harsh environments

A methodology for design of lightweight robotic arm links in harsh environments

Lightweight design is crucial in today’s world to improve efficiencies, reduce costs and bring benefits to the environment. The use of robots is ever- increasing in various sectors of society, from use in industry to use in the home. There is therefore a need to understand how to extract the greatest benefit from robots as possible, including making them as light as possible. Work on lightweight robotic design has featured heavily on re-design of actuators and drive systems [1]–[3][4]–[6]. Links have not received as much attention [7]. The aim of this paper is to outline a methodology for the design of lightweight robotic arm links. The methodology has mechanisms for the inclusion of graded materials. Graded materials allow the designer to combine materials to take advantage of their different material properties. Advantages range from different densities to allow certain regions to be made from lighter materials, to different thermal conductivities to allow for different heat flow characteristics. The methodology differs from previous functionally graded material (FGM) methodologies ([8][9][10]), as it designs parts with the manufacturing constraints already in mind, rather than retro fitting the methodology around current parts.
Show more

10 Read more

Improving the yield and lifetime of microfabricated sensors for harsh environments

Improving the yield and lifetime of microfabricated sensors for harsh environments

Following further examination of the device, metallic deposits were observed on the edge of the exposed Si, around the perimeter of the chip. Figure 11 (a) shows the edge of the Si after dicing and (b) after the silver plating experiment, with (c) showing a more magnified image of this edge. To confirm that these deposits were the plated silver, a SEM with EDX (Energy-Dispersive X-ray) spectroscopy was used to image and measure the elemental composition of the deposits. A SEM image of such a deposit is presented in figure 12 along with its elemental breakdown in the inset, which confirms that the metallic deposits observed on the Si edge are silver. It should be noted that at 450°C, Si behaves as a conductor, owing to the thermal excitation of intrinsic charge carriers into the conduction band. The silver plating observed on the Si suggests that defects are connecting the electrode metal to the underlying Si. Hence, the observed insulator failure is associated with the underlying thermal SiO 2 layer rather than
Show more

8 Read more

Investigation of the response of high bandwidth MOX sensors to gas plumes for application on a mobile robot in hazardous environments

Investigation of the response of high bandwidth MOX sensors to gas plumes for application on a mobile robot in hazardous environments

The base of the tunnel (formed from an acrylic sheet) was divided into 9 sections (3 × 3 grid), as shown in Fig. 3. The concentration of the plumes of VOC generated in the wind tunnel were measured at each of the 9 locations. The sensor module is shown positioned in the wind tunnel at location B2, with the gas inlet facing the VOC source. A Teensy microcontroller (version 3.2, PJRC) was used to control the rotation speed of the fan, via PWM (Pulse Width Modulation), and thus the air flow through the tunnel; wind speeds were verified using a thermal anemometer (405i, Testo). The air flow speed could be varied between 1.3 m/s and 2.3 m/s. The lower speed was used in these measurements, to closely resemble the speed at which the mobile robot can travel (~ 5 km/h).
Show more

42 Read more

Precision Assessment of UAVRS Based DSM in Disaster Emergency

Precision Assessment of UAVRS Based DSM in Disaster Emergency

Ground control point (GCP) is important for georeferencing remotely sensed images and topo- graphic model. However, considering that GCP collection is sometimes a difficult, time-consuming and expensive task with high resolution (HR) data in remote and harsh environments, today un- manned aerial vehicle based remote sensing (UAVRS) is frequently used in geological disaster emergency monitoring and rescuing for its great advantage in collecting timely onsite images. In this paper, for evaluating the feasibility of the UAVRS in disaster emergency and high cut slope safety monitoring, the digital surface model (DSM) without GCPs based on Structure from Motion (SfM) is accessed, and results showed that the geometric accuracy of DSM was smaller than 1 per- cent, which prove the usefulness of DSM based on UAVRS in emergency. Comparing to normal dis- aster emergency, the method without GCPs can be more efficient and save the disaster emergency time by neglecting GCPs measurement.
Show more

11 Read more

Silicon micromachined flow sensors

Silicon micromachined flow sensors

18.1 Standard piranha wafer cleaning omitted if immediately follow step #17.. 19.3 Standard photolithography 6 μm photoresist.[r]

13 Read more

Measurement Technologies for Urban Heat Islands

Measurement Technologies for Urban Heat Islands

Changes in land use, the share of impervious surface varies with land use and zonation of the urban plan. This changes the heat flux, and increases the land surface temperature. Increased temperature leads to adverse climate and also increases the energy use for air conditioning and the pollution level. Surface and atmospheric modifications due to urbanization generally lead to a modified thermal climate that is warmer than the surrounding non-urbanized areas, particularly at night. This phenomenon is the Urban Heat Island (UHI).
Show more

7 Read more

Human error risk assessment for shipping maintenance procedures in harsh environments

Human error risk assessment for shipping maintenance procedures in harsh environments

Abstract – Human factors play a significant role in increasing the operational safety of maritime transport and offshore facilities. A significant number of human errors occur during the maintenance phase. However, the qualification of human error interpretation before undertaking any quantification in the maintenance procedure should be given more attention. It is necessary to find a reasonable qualitative non-linear based method with good interpretation of WHY and HOW accidents occur. This provides good insight, sources of risk and the possibilities for minimizing the potential risk. As maritime operations move into Arctic and Antarctic environments, this will become even more crucial. Decision makers must therefore be able to recognize how cold weather affects human performance and work out how availability, survivability or maintenance of a system goes wrong. This will help assessors to review the details of the process and ask relevant questions rather than blindly finding answers. This paper presents a new reciprocal interaction of qualitative risk-based methodology for human error estimation by applying “Functional Resonance Analysis Method” (FRAM). This methodology has the potential to be considered the first step of any future quantitative assessment for human error estimations. The present study is an imperative milestone for coupling between nonlinear qualitative and quantitative based methods in risk assessment to systematically identify human errors. The developed methodology has been applied to a case study for the maintenance of a component in a ship sailing in a harsh environment.
Show more

6 Read more

Auto sensor deployment and local coverage-aware recovery schemes for smart environments

Auto sensor deployment and local coverage-aware recovery schemes for smart environments

field and disk packing theory. Though sharing similar idea of virtual forces with [42], our EVFA- B deals with both the homogeneous and heterogeneous sensors, while [42] only discusses the case of homogeneous sensors, where a global distance threshold value is adopted in determining whether an attractive (with weight constant wa) or repulsive (with weight constant wr) force should be applied on a sensor. However, in realistic settings, where varying sensing distances are common, the distance threshold (determining the desirable sensing overlapping degree) should be selected on a node- pair basis, instead of being set globally. In addition, since the observed environment is usu- ally in a bounded area, our EVFA-B incorporates the boundary force (with weight constant wb) as a kind of repulsive force from the boundaries to keep sensors staying inside the monitoring area. Since the boundary force is considered as a type of repulsive force, we use the same value for wr and wb. In [42], no boundary force is modeled, and no specific design guide- lines are available for determining suitable wa and wr (¼ wb) weight constants. Motivated by the observations, we investigate and conjecture that good choices for wa and wr (¼ wb) greatly depend on sensor population and monitored area dimensions, while independent of sensing radius.
Show more

5 Read more

Correlating sensors and activities in an intelligent environment: A logistic regression approach

Correlating sensors and activities in an intelligent environment: A logistic regression approach

It is important to emphasize that in a ubiquitous environment that is saturated with sensors, it is extremely important to distinguish the critical set of sensors that correlate with a specific activity from others that do not. For example, imagine constructing a Bayesian network for the activities in a ubiquitous space without knowing the dependencies between sensor readings and the activities. Including uncorrelated sensors in the Bayesian network will result in inaccuracies that can potentially misguide the reasoner. Similarly, excluding correlated sensors from the Bayesian network could result in ignoring some important aspects of the activities that can also misguide the reasoner. This paper focuses on how to determine the critical set of sensors that correlate to activities and proposes a new technique for accomplishing that. We begin our discussion by examining some of the desirable properties for activity-aware intelligent systems.
Show more

8 Read more

RF Sensing Based Target Detector for Smart Sensing Within Internet of Things in Harsh Sensing Environments

RF Sensing Based Target Detector for Smart Sensing Within Internet of Things in Harsh Sensing Environments

alarm rates of the decisions taken based on the data from a single sensor can be as high as 60 percent [13]. In [10], authors have proposed an IoT with multiple sensor nodes distributed within the sensing region. Varshney [14] discussed data fusion to improve the target detection reliability. A net- work of distributed sensor nodes is designed in [15]–[17] where the sensors are grouped together by a control centre which can adopt joint scheduling approach [18]. The dis- tributed network can provide improved sensing coverage and connectivity with efficient energy consumption. A distributed network of sensor nodes can be seen as a multiple-input multiple-output (MIMO) system that transmits a waveform of known shape and detects the reflected echoes from the target. The presence of multiple sensor nodes within the sensing region increases the probability of detecting the presence of targets. However, the signals transmitted from the neighbour- ing sensor nodes interfere with each other and reduce the target detection reliability. In the existing literature, various target detectors [19]–[24] have been proposed by the authors to provide improved target detection performance. However, the proposed target detectors are computationally intense and incompatible with resource constrained IoT. The presence of objects within the sensing region, which interact with the transmitted signal result in clutter returns. Since, clutter returns appear similar to the target returns, the presence of clutter leads to increased false detection rates and reduced reliability. In this paper, we design a target detector, which operates within the sensing and operational constraints of IoT. The proposed target detector is expected to provide an accept- able trade-of between power consumption, target detection reliability and computational complexity.
Show more

18 Read more

Adaptive inventory management system of an industrial enterprise in the unsteady market environment

Adaptive inventory management system of an industrial enterprise in the unsteady market environment

The research results confirm the constructibility of the considered principles of methodology and inventory management system construction, as well as the performance of the proposed algorithms for the estimation of unknown parameters of demand. Thus, it can be stated that the proposed adaptive strategy and the model of operational inventory management could well be used in harsh environments typical of the unsteady economy, namely in terms of significant and unforeseen fluctuations in the stochastic parameters of demand during delivery period.

5 Read more

Thermal Conductivity Sensors in Automotive Applications

Thermal Conductivity Sensors in Automotive Applications

There are a lot of hydrogen sensors potentially applied in automotive industry. However, there is not a single sensor that meets all requirements for all applications, and no sensor is ideal for all applications. Requirements differ significantly. For hydrogen safety, sensors are typically calibrated to trigger warnings before the hydrogen concentration reaches the lower flammable limits (LFL) of hydrogen since the LFL of hydrogen is 4% (by volume) in air, e.g.: warnings at 5% of the LFL and 15% of the LFL and an alarm at 25% the LFL; these warning and alarm thresholds may represent a certain hydrogen concentrations like 0.2%, 0.6% and 1% in volume respectively. Then, the leak detection system indicates an alarm in order to activate protective measures before gas concentrations reach a dangerous level [33].
Show more

101 Read more

Energy Efficient Link-Delay Aware Routing Using Predicted Remaining Deliveries in Wireless Sensor Networks

Energy Efficient Link-Delay Aware Routing Using Predicted Remaining Deliveries in Wireless Sensor Networks

Self organizing, wireless sensors networks are associate emerging and difficult technology that's attracting massive attention within the sensing and watching community. Several routing protocols are projected among these protocols, the adjustive routing protocols are terribly engaging as a result of they need low routing overhead. As a result, the routes tend to own the shortest hop count and contain weak links that typically give low performance and are prone to breaks. during this paper we tend to introduce associate adjustive routing protocol referred to as energy aware routing that's supposed to supply a reliable transmission surroundings with low energy consumption. This protocol with efficiency utilizes the energy handiness and also the received signal strength of the nodes to spot the simplest potential route to the destination. Simulation results show that the energy aware routing theme achieves a lot of higher performance than the classical routing protocols, even within the presence of high node density and overcomes coincidental packet forwarding.
Show more

6 Read more

Mechanisms of cyst formation in metastatic lymph nodes of head and neck squamous cell carcinoma

Mechanisms of cyst formation in metastatic lymph nodes of head and neck squamous cell carcinoma

It is possible that a cystic carcinoma in a lymph node be a primary tumor or have origination from a benign cyst already present in the lymph node. However, these probabilities seem to be a hypothetical entity, or an extremely rare event [7]. Cystic SCC in metastatic cervi- cal lymph nodes is now considered as a typical presenta- tion of SCC arising in the oro/nasopharynx [7]. It has been suggested that this phenomenon is secondary to pseudocystic change and results from spontaneous degradation of keratin and cellular debris within the car- cinomatous lymph node deposit [5]. Probably cyst for- mation in these cases could also be related to the sudden blockage of lymphatic flow passing through a node that has metastatic colony. This lymphatic fluid fills a potential space, which have tumor cells in periph- ery [8].
Show more

5 Read more

Transcriptional analysis of biofilm formation and stress response in hyperthermophilic microorganisms.

Transcriptional analysis of biofilm formation and stress response in hyperthermophilic microorganisms.

specific lectins), in addition to others (e.g., chemotaxis (193), physicochemical forces (67), etc.), may take place in deep-sea hydrothermal vents. Alteromonas and Vibrio spe- cies have been isolated from the polychaete annelid (i.e., worm) Alvinella pompejana that inhabit hydrothermal vent systems (206, 207, 220-223). In addition, the exopolysaccha- rides of a biofilm may serve as a nutrient source for nearby microorganisms. Hyperther- mophiles and mesophiles could use an array of glycosidases (e.g., endoglucanases, amy- lases, pullanases, and mannanases) for recruiting carbon and energy sources from envi- ronmental pools. While numerous studies have documented the diffuse flow of ions and metals in hydrothermal vent systems (266, 267), the flux of polysaccharides in these en- vironments has not been studied. This is due to the difficulties associated with sampling vent systems and the recent identification of polysaccharides in these environments (112, 221). Thus, the ecological interaction of hyperthermophilic and mesophilic microorgan- isms and polysaccharides needs to be addressed. These interactions could provide insight into the metabolic, genetic, and evolutionary relationships within extreme environments.
Show more

165 Read more

Protecting Data Confidentiality from Leakages in Harsh Environments Using a Accountable Data Transfer Protocol
Ahmed Tamem Mohammed Alkhbeer & T Ramdas Naik

Protecting Data Confidentiality from Leakages in Harsh Environments Using a Accountable Data Transfer Protocol Ahmed Tamem Mohammed Alkhbeer & T Ramdas Naik

Additionally, most of these approaches only allow identification of the leaker in a non-provable manner, which is not sufficient in many cases. We present a generic data lineage framework LIME for data flow across multiple entities that take two characteristic, principal roles (i.e., owner and consumer). We define the exact security guarantees required by such a data lineage mechanism toward identification of a guilty entity, and identify the simplifying non-repudiation and honesty assumptions. We then develop and analyze a novel accountable data transfer protocol between two entities within a malicious environment by building upon oblivious transfer, robust watermarking, and signature primitives.
Show more

8 Read more

Show all 10000 documents...