Ambient environmental sensors

Sensors are fundamental components of all sensor networks, and their quality depends heavily on industry advances in signal conditioning and processing, microelectrome-chanical systems, and nanotechnology. Sensors are classified into three categories physiological, biokinetic, and ambient environmental sensors. 

Ambient air flow or forced convection can also be a source of energy for distributed environmental sensors or similar autonomous devices exposed to a flow. The airflow can induce the rotation of a microturbine (similar to large-scale wind mills) or the oscillation of a structure. This mechanical energy can then be converted to electricity by electromagnetic, piezoelectric, or electrostatic principles. 

Durability Ambient, body, and environmental sensors are subject to various weather challenges and hazards but need to be able to maintain their operation and functionality for long periods of time, regardless of the conditions that they are facing. 

Some tanks are installed with permanent leak identification sensors, which can check for leaked fuel vapor or liquid as it comes into contact with the sensors.21 However, these, as well as all the environmental sign tests (visual or instrumental) may be triggered by a spill instead of a leak. The success of external systems depends on the sensitivity of the sensor, the ability of the sensor to distinguish the stored chemical from other chemicals, the ambient background noise level of the stored chemical, the migration properties of the chemical, and the sampling network. 

In this paper we consider SHP as a combination of a loop heat pipe (LHP) and ammonia/ (active carbon fiber -I- chemicals) solid sorption cooler. Such system extends the limits of two-phase thermal control and ensures successful mode of electronic components cooling even in very harsh environmental conditions (ambient temperature 40 °C, or more) and ensures a deep cooling of space sensors down to the triple point of the hydrogen. 

The mechanical properties of thin films used as membranes or moving structures and produced either by bulk or surface silicon micromachining are of crucial importance. In either type of application, the mechanical stress and the fracture properties of the applied thin films determine the behavior and long-term reliability of the device. In automotive applications, the environmental constraints (e.g., high ambient temperatures and temperature variations) and the required long life expectancy of the sensors require the use of high-quality thin films with well-controlled properties. 

The more sophisticated injection-humidity cabinet permits a wide variation in temperature and humidity to be created with a few simple settings of the controls. The humidity is measured by a suitable moisture sensor, such as a wet and dry bulb hygrometer or capacitive sensor, and this is used to control the injection of moisture into the chamber. Through the use of suitable control circuits it is also possible to cause such a chamber to cycle in temperature and/or humidity so that varying ambient conditions over wide extremes may be simulated for assessing such effects on the environmental resistance of polymer products. 

Biokinetic sensors measure acceleration and angular rate of rotation derived from human movement. For certain kinetic movement detection, sensors are based on strain gauges, accelerometers, and global positioning system (GPS). Ambient sensors measure environmental phenomena, such as humidity, light, sound pressure level, and temperature. 

The reactor is normally associated with chemical processes, but work in the US is directed at developing enzymatic micro-reactors . It is believed that these could be used as sensors, for energy production, chemical synthesis and environmental clean-up. The inherent advantage of enzymes in reactors is that they operate at ambient temperatures and pressures. This, of course, potentially leads to less complex engineering than that necessary for most chemical micro-reactors. 

Optical sensors offer some advantages over electrochemical methods [10, 11]. First, no reference electrode is required however, reference intensity is necessary to minimize environmental effects on the system. Second, fiberoptic sensors are immune to electrical noise, but ambient light can be a problem. Finally optical sensors have the potential for higher information content than electrical sensors because there is a complete spectrum of information available. However, the linearity is usually limited to a very narrow range. 

---