Weight sensors

Goelen E, Lambrechts M, Geyskens F, Rymen T 1992) Development and performance characteristics of a capillary dosage unit with an in situ weight sensor for the preparation of known amounts of gaseous VOC s in air. Intern J Environ Anal Chem 47 217-225. 

In some other washing machines that have recently entered the market, the wash load is detected by a weight sensor that measures the elongation of the spiral springs where the tub is suspended inside the washing machine. This is known as a load size indicator . Based on information from the detergent manufacturer, it tells the customer how much detergent to use. 

Several new sensors will have to be introduced alongside the current ones - several types of temperature sensors, level sensors, load and weight sensors, humidity sensors etc. 

Costin, C.D., Synovec, R.E., A microscale-molecular weight sensor probing molecular diffusion between adjacent laminar flows by refractive index gradient detection. Anal. Chem. 2002, 74, 4558 1565. 

The accuracy of WIM systems generally depends on a number of factors. Some of them depend on the system selected, particularly on the weight sensor used. Others are consequent to WIM technology and are related to the road geometry, pavement characteristics and environmental characteristics or requirements. 

The weight sensor is the most fundamental and important component of a WIM system. The sensor or sensors are placed on or within the pavement, perpendicular to the direction of traffic. Depending on how they are placed, the sensors can be temporary, semi-permanent/temporary or permanent. 

Temporary weight sensors are surface mounted and fixed so that they can be removed and re-installed at another location. Semi-temporary weight sensors are similar to the temporary ones, but only one component of the sensor is removed and re-installed (the gauge, transducer or signal processor). Permanent weight sensors are installed to the surface (or at a certain depth) once and are not removed until they are damaged. 

The classification of vehicles is carried out through various types of sensors, which are placed close to the weight sensor. The typical vehicle classification sensors include loops, piezo-electric cables, mechanical switches and tubes. 

The data storage and processing unit is placed at the roadside and in a protective cabinet. This unit is connected to the weight sensors, the vehicle classification sensor and the vehicle identification sensor. With the aid of software, it has the ability to present brief and analytical results. The data storage and processing unit also powers the WIM system the power is supplied by mains, rechargeable electric or solar batteries. 

There are various factors affecting the performance of a WIM system. Some of them are related to the selected device, particularly the weight sensors used and related technology. However, the performance of a WIM system is greatly affected by the choice of the WIM site and the environmental characteristics at the selected site. In relation to the choice of site, the location and road geometry, the pavement characteristics are of great importance as well. 

If the valve is opened by some amount, increasing the material on the belt, there will be a delay equal to minutes before the increased weight is sensed at the weight sensor/transmitter. 

Using the weighing system example of dead time, a 10 kg increase in material on the conveyor belt would result in a 10 kg increase at the weight sensor or a static gain of one. Similarly, it can also be shown that the above analysis holds for the pipe flow situation. In each of these cases a pure dead time exists since Kss = However, consider the scenario shown in Figure 3.22. 

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