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Automatic controls monitor certain data of 
environmental disaster characteristics. When specific 
conditions are met, control decisions are automatically 
changed without operator or manager intervention. 
Automatic controls can be either global or local. 
5.4 Manual control 
Manual control processes either permit or require 
human intervention. Environmental disaster 
management alter control decisions using these 
processes. Clearly, the role of the MIB is to provide the 
disaster manager with information that supports 
decision making regarding the disaster. This 
supporting activity may be achieved passively by simply 
providing an interface between the disaster manager 
and disaster status information. Alternatively, it may be 
achieved through an alarm system that notifies the 
disaster manager of environmental disaster conditions. 
6. SURVIVABILITY ANALYSIS 
Interest in reliable and robust agricultural production 
system has been increasing in recent years. As a result, 
there is a growing need for ensuring that agricultural 
production systems maintain service despite outages 
such as environmental failures or disasters. This 
desired service or quality is called survivability of 
agricultural production system. 
Due to the lack of feasible computational methods for 
evaluating survivability of a large complex and 
heterogeneous agricultural production system, some 
evaluation — systems must be developed for the 
application need. This is particularly true in the area of 
survivability management of agricultural production 
systems, which has been recognized as one of the main 
task of design of modern agricultural production 
system. The requirement of this approach, usually, is a 
short development cycle and the fact that it can be 
easily applied to analyze the survivability of complex 
agricultural production system. 
Another requirement is to evaluate survivability of 
agricultural production system through analysis for 
policy hierarchy. Under this case, survivability of an 
agricultural production system can be modeled by a 
probability model. 
Elements of agricultural production system can fail for 
any number of reasons, including architecture defects, 
design — defects, and inadequate maintenance 
procedures. Intrusions can come from acts of 
earthquake, flood, hurricane, and other accidents 
related to environmental disaster. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998 
6.1 Integrity 
The integrity problem of optical communication system 
has been discussed in (Wu, 1992), which has provided 
a number of valuable experiences for the similar study 
of other system. The integrity of agricultural production 
system is defined as: the ability of an agricultural 
production system provided to deliver high quality, 
continuous service while gracefully absorbing, with 
litter or no customer impact, failures of or intrusions 
into the hardware or software of elements of 
agricultural production system under environmental 
disaster. 
The quality of agricultural production system can be 
evaluated by its integrity, which belongs to three major 
categories as the followings. 
(1) Agricultural production system availability deals 
with the fraction of time that the agricultural 
production system is in normal service. For 
example, a metric is purposed to measure the loss of 
agricultural products in units of dollars/year under 
environmental disaster, in order to evaluate the 
quality of agricultural production system. 
(2)After-disaster survivability assumes that some 
environmental disaster has occurred. Usually, the 
worst-case single or more disasters are considered 
for computing the quality of agricultural production 
system. 
(3)Disaster-based survivability considers what happens 
in the wake of a disaster. The occurrence of a 
disaster event is used as a given assumption. For 
example, in the case of a large-scale environmental 
disaster, failures of several agricultural production 
components or elements of agricultural production 
system could happen simultaneously. In general, the 
agricultural production system may fail totally, 
partially, or not at all. Thus, the analysis result can 
be used for computing the quality of agricultural 
production system. 
6.2 Survivability 
On the other hand, traditional design methods of 
agricultural production system aim at satisfying some 
specified performance objectives under normal 
conditions without explicit consideration of agricultural 
production system quality or survivability. However, 
performance under environmental disaster can be 
unpredictable for agricultural production systems 
designed based on these methods. But, a major benefit 
of setting survivability performance objectives will be to 
ensure that, under given disaster scenarios, agricultural 
production system performance will not degrade below 
predetermined levels. Further, such a set of 
performance objectives should be used to realize design 
and management goals of agricultural production 
system. 
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