Passive Safety Measures

In what follows the principle of a passive safety measure is explained using the design and functioning of the passive emergency trip system shown in Fig. 4.4 as an example [15]. 

Explosion-proof design implies that all structures potentially affected by an explosion can withstand the maximum pressure and the maximum pressure rise caused by a confined explosion. Details on confined explosions of flammable gases are found in Sect. 2.1.1.10 and of flammable dusts in Sect. 2.4.6. In considering this it must be kept in mind that the initial pressure of an explosion can be above atmospheric depending on process conditions. This leads to a corresponding increase of the maximum pressure. Explosion-proof design is an example for a passive safety measure. 

At present, pedestrian protection requirements mainly involve optimization and implementation of passive safety measures at vehicle front ends, where most pedestrian impacts occur. The most prominent improvements have involved changes in the shape of the front end and the elimination of sharp or rigid mounted parts, e.g., bull bars [40], in order to minimize obvious sources of injury. Another important passive... 

All passive safety measures implemented in the vehicle are only capable of addressing the so-called primary collision (i.e., contact with the vehicle). For example, only about 6 % of pedestrians impact with the head on the hood, which limits the efficacy of measures implemented there [48]. Secondary collisions, i.e., contacts with the road surface or other objects, are not addressed by those measures. In contrast active safety measures address the entire sequence of events and as a consequence have a much higher injury avoidance potential [17,49]. Preventive systems are at the moment in the state of development or already in the market [48, 50-52],... 

The first one focuses on the evaluation of passive safety measures and is called the injury shift method. The basic idea is that a passive safety measure has a positive effect on the severity of injuries sustained at a specific component. The assumption is that below 40 kph, optimized components result in a reduction of one level on the abbreviated injury scale (AIS) [50] (for a detailed description of AIS see Sect. 5.1,... 

One example of a component-based testing method is the Vehicle Related Pedestrian Safety Index (VERPS) [73, 74]. This index utilizes a linear scale for both active and passive safety measures. The pedestrian head impact in frontal passenger vehicle collisions is assessed using the Head Injury Criterion (HIC) as metric. The method delivers specific results for a given vehicle and pedestrian combination. The evaluation process includes accident data analysis for relevant scenarios, kinematic analysis (via multi-body simulation), hardware component testing, and a procedure to obtain the VERPS index [73, 74]. The VERPS index takes only the probability for AIS3+ head injuries due to impact on the vehicle into account, since this probability can be derived from the HIC measurement. 

Personal protective equipment (PPE) has a twofold role in the workplace. In some cases it is a passive safety measure, used to minimize injmy if other protective measures fail. But it is also used as the main means of injttry prevention in situations where it is impossible to guarantee the effectiveness of other safety measures, e.g. penetration-resistant boot soles on a construction site, fall arrest harnesses where falls are likely to cause serious injtrry or death. 

Passive safety measures that do not rely on control systems, active safety systems or human intervention. 

Adopted the use of simple passive safety measures requiring only the one time re-alignment of valves. These systems do not require support systems, such as ac power (from offsite or onsite), cooling water systems (such as component cooling or service water) and heating, ventilation and air-conditioning (HVAC) systems. 

Industrial fire protection and safety engineers attempt to eliminate hazards at their source or to reduce their intensity with protective systems. Hazard elimination may typically require the use of alternative and less toxic materials, changes in the process, spacing or guarding, improved ventilation or, spill control or inventory reduction measures, fire and explosion protective measures - both active and passive mechanisms, protective clothing, etc. The level or protection is dependent on the risk prevalent at the facility versus the cost to implement safety measures. 

However, it is conceivable that no inherent safety measures exist for a given process. In such a case only engineered safety measures inscribed in the categories of Table 4.2 (passive, active, organizational) can be applied. 

VII.73. An example of variability in measurement technique is provided by France, which currently specifies the use of a simple gamma detector measurement to verify bumup credit allowances for less than 5600 MW d/MTU but more direct measurement of fuel bumup for allowance of higher irradiation [VII.39]. For this second measurement, France rehes on two instruments that verify the reactor bumup records based on active and passive neutron measurements. In the USA a measurement device similar to one used in France has been demonstrated by Ewing [VII.40, VII.41] to be a practical method for determining if an assembly is within the acceptable fuel region of Fig. VII.2. If the axial bumup profile is identified as an important characteristic of the spent nuclear fuel that is relied upon in the safety analysis, then similar measurement devices could also potentially be used to ascertain that the profile is within defined limits. 

The concept of Integral Safety is a holistic approach to vehicle safety including active and passive safety as well as the direct interaction of both. The primary objective is to provide a high level of safety during all phases of an accident as a result of an effective combination and interaction of measures of both active and passive safety [14, 17, 27, 28]. 

Interpreting these statistics regarding the effect of active and passive safety, the following observations can be made The decreasing accident rate (fairly constant number of accidents for increasing Icm driven) strongly suggests that measures for... 

The first consideration of active safety in regulations is included in (EC) No. 78/2009[37], Chapter III Article 11. All vehicles equipped with collision avoidance systems may not have to fulfill the test requirements laid down in Sections 2 and 3 of Annex I in order to be granted an EC type-approval or a national type-approval for a type of a vehicle with regard to pedestrian protection, or to be sold, registered or to enter into service . It is required that [a]ny measures proposed shall ensure levels of protection which are at least equivalent, in terms of actual effectiveness, to those provided by Sections 2 and 3 of Annex I . Article 11 provides a legal basis for future fulfillment of the regulation by both active and passive safety devices, based on the effectiveness required. 

The approval process for braking assistance can be regarded as a prerequisite for active safety systems. The requirements formulated by the Directive 2003/102/EG, Phase 2, of the European Parliament and of the Council [53] could nearly not be fulfilled by means of passive safety. As a consequence, an evaluation regarding the effectiveness of different measures of pedestrian protection has been carried out [54, 55]. The commitment of the European Automobile Manufacturers Association (ACEA) European Automobile Manufacturers Association to implement brake assist, an active safety system, in every new car, led to a reduction of the requirements... 

The next evolution of the method presented by Busch is called PreEffect-iFGS. It is a prospective method for evaluating the field effectiveness of integral pedestrian protection systems [21]. The main procedures of Busch, i.e., selection of relevant accidents, simulation with/without system, translation into injury severity, and calculation of the effectiveness, stayed the same with some additions. The improvement is an incorporation of test results for active and passive safety systems derived from hardware testing [54]. The initial version also includes an automated backwards simulation of each accident based on the values available in GIDAS. The results are then transferred into the commercial software PC-Crash and are then simulated forward with and without the measure in question. 

Htimacher, M., Eckstein, L., Kiihn, M., Hummel, T. (2011). Assessment of active and passive techniceil measures for pedestrian protection at the vehicle front In 22st International TechniccU Conference on the Enhanced Safety of Vehicles (ESV 2011), No. 11-0057. 

Passive safety. If hazards cannot be avoided and there is a need to add safety measures, use passive protective measures instead of active or procedural measures. 

Dunng four winters of NHR-5 heaung operation, the reactor has been known as a valuable tool for a number of e.xperiments on operation behaviors and safety features The operational and experimental results have successfully demonstrated the inherent and passive safety characteristics of NHR-5 It was pro en tiiat the design concept and technical measures of HR are suitable to meet the requirements for disinc heating in nortliem cities, congeneration and air condition in the middle aties of China, as well as the seawater desalination... 

We shall consider users not only as passive objects for risk mitigation but also as subjects that can compromise their own safety. Safety measures can be more or... 

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