Abstract:
A HAZMAT monitoring system detects a plurality of different hazardous materials and includes first and second pluralities of RSIs. Each RSI of the first plurality forms a node in a first wireless sensor network and is associated with a mobile container and with at least one sensor that is configured to acquire data for detecting a first hazardous material. Each RSI further is configured to receive the sensor data and wirelessly transmit, over the first wireless sensor network, data relating to the received sensor data pertaining to the detection of the first hazardous material. Each RSI of the second plurality is similarly associated and configured. Communications within a respective wireless sensor network do not result in communications within the another wireless sensor network. A gateway is configured to independently communicate with each respective wireless sensor network.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation of, and claims priority under 35 U.S.C. §120 to, Twitchell U.S. Nonprovisional Patent Application No. 12/774,586, filed May 5, 2010, which &#39;586 Application published as U.S. Patent Application Publication No. 2010/0214059, and which &#39;586 Application a continuation of, and claims priority under 35 U.S.C. §120 to, Twitchell U.S. Nonprovisional Patent Application No. 12/495,716, filed Jun. 30, 2009, which &#39;716 Application issued as U.S. Pat. No. 7,847,676, and which &#39;716 Application is a continuation of, and claims priority under 35 U.S.C. §120 to, Twitchell U.S. Nonprovisional Patent Application No. 11/425,047, filed Jun. 19, 2006, which &#39;047 Application issued as U.S. Pat. No. 7,554,442 and which &#39;047 Application is a nonprovisional of, and claims priority under 35 U.S.C. § 119(e) to, Twitchell U.S. Provisional Patent Application No. 60/691,574 filed Jun. 17, 2005. The entire disclosure of each of these patent applications, publications, and patents is hereby incorporated herein by reference. 
     
    
     INCORPORATION BY REFERENCE 
       [0002]    The present application hereby incorporates by reference: U.S. Pat. No. 6,753,775 B2 (titled “Smart Container Monitoring System”); U.S. Pat. No. 6,745,027 B2 (titled “Class Switched Networks for Tracking Articles”); U.S. Pat. No. 6,665,585 B2 (titled “Method and Apparatus for Container Management”); U.S. Pat. No. 5,458,042 (titled “Container for Packaging an Object Provided with a Radio Frequency Transmission Device and Removable Element for Such a Container”); International Patent Application Publication No. WO 03/032501 A2, which international patent application designated the United States and was published in English (titled “Network Formation in Asset-Tracking System Based on Asset Class”); International Patent Application Publication No. WO 03/098851 A1, which international patent application designated the United States and was published in English (titled “LPRF Device Wake Up Using Wireless Tag”); U.S. Patent Application Publication No. 2005/0093703 A1 (titled “Systems and Methods Having LPRF Device Wake Up Using Wireless Tag”); U.S. Patent Application Publication No. 2005/0093702 A1 (titled “Manufacture of LPRF Device Wake Up Using Wireless Tag”); U.S. Patent Application Publication No. 2004/0082296 A1 (titled “Network Formation in Asset-Tracking System Based on Asset Class”); U.S. Patent Application Publication No. 2004/0183673 A1 (titled “Portable Detachable Self-Contained Tracking Unit for Two-Way Satellite Communication with a Central Server”); and U.S. Patent Application Publication No. 2004/0021572 A1 (“Electronic Baggage Tracking and Identification”); U.S. patent application Ser. No. 11/422,321 (titled “Remote Sensor Interface (RSI) Stepped Wake-Up Sequence”), which published as U.S. Patent Application Publication No. 2006/0276161 A1; and U.S. patent application Ser. No. 11/423,127 (titled “All Weather Housing Assembly For Electronic Components”), which published as U.S. Patent Application Publication No. 2006/0289204. 
       COPYRIGHT STATEMENT 
       [0003]    All of the material in this patent document is subject to copyright protection under the copyright laws of the United States and other countries. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in official governmental records but, otherwise, all other copyright rights whatsoever are reserved. 
       FIELD OF THE INVENTION 
       [0004]    The present invention generally relates to the monitoring of materials and, in particular, hazardous materials. Furthermore, the present invention relates to mobile containers of such materials and sensors associated therewith for monitoring of the mobile containers. The descriptions herein relate to mobile containers and vehicles that are in motion as well as to mobile containers and vehicles that are stationary. 
       BACKGROUND 
       [0005]    A 1997 Hazardous Material Shipment Study commissioned by the U.S. Department of Transportation (USDOT) indicates that approximately 3.1 billion tons of hazardous materials were transported in the United States in 1997, which is roughly 8.5 million tons per day. Specifically, approximately 0.5 billion tons of chemicals and 2.6 billion tons of petroleum products were transported in 1997. Furthermore, between 1996-2005, there were more than 150,000 hazardous material transportation incidents reported to the USDOT. The USDOT defines hazardous materials (HAZMAT) as belonging to one of nine classes of materials, including explosives, gases, flammable solids, flammable liquids, oxidizers and organic peroxides, toxic materials and infectious substances, radioactive materials, corrosive materials and miscellaneous dangerous goods. Each of these classes of materials is dangerous and potentially harmful to people, and therefore, caution should be utilized in their handling and transportation. Accordingly, it is important to be able to accurately and efficiently monitor the transportation of such hazardous materials. 
         [0006]    Monitoring may include asset tracking or it may include incident notification in the event of an incident such as a leak or spill of hazardous materials. Monitoring sensors are known that can quickly and accurately detect a hazardous material incident. For example, U.S. Patent Application Publication No. 2005/0046567 discloses a sensor for monitoring the internal environment of a container. However, a monitoring network that efficiently integrates and connects such available sensors is desired. 
         [0007]    Unfortunately, a more recent issue with hazardous materials is concern regarding the administration of chemical weapons. Risk of introduction of a terrorist biological, radiological or explosive device via a transportation container is high, and the consequences to people and property surrounding such container could be catastrophic. Further, such a terrorist incident could cripple the international economy because of the importance of transportation containers in world commerce. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention includes many aspects and features. 
         [0009]    A wireless sensor network for monitoring of a container includes a sensor disposed for monitoring of a container, at least one remote sensor interface, and a gateway. The sensor is configured to acquire data related to the container and communicate sensor data as a function of the acquired data. The remote sensor interface is configured to receive the sensor data communicated from the sensor and wirelessly transmit data relating to the received sensor data. The gateway is configured to receive data related to the sensor data, and transmitted from the at least one remote sensor interface, and is configured to communicate data relating to the sensor data to a network external to the wireless sensor network. The gateway is in at least intermittent electronic communications with the external network. 
         [0010]    In a feature of the invention, the sensor is a chemical sensor. In accordance with this feature, the chemical sensor may be sensitive to a chemical present within the container. 
         [0011]    In a feature of the invention, the sensor comprises a biological sensor, a radiological sensor, a nuclear sensor, an explosive sensor, or a chlorine sensor. 
         [0012]    In a feature of the invention, the sensor detects a particular chemical, substance, or biological agent. 
         [0013]    In a feature of the invention, the sensor comprises a seal monitor that detects openings and/or closures of a container. 
         [0014]    In a feature of the invention, the sensor comprises an inclination monitor for detecting the overturning or tipping of a container. 
         [0015]    In a feature of the invention, the sensor comprises a device or array of devices for measuring state conditions of a container. 
         [0016]    In a feature of the invention, the sensor comprises a device or array of devices for measuring state conditions of contents of a container. In accordance with this feature, the state condition is at least one of temperature, volume, weight, and pressure. 
         [0017]    In a feature of the invention, the sensor comprises an activity monitoring device. 
         [0018]    In a feature of the invention, the activity monitoring device comprises at least one of a microphone, a motion detector, a light detector, and a broad-band RF signal scanner. 
         [0019]    In a feature of the invention, the sensor comprises a device for detecting at least one of physical presence at a container, movement of a container, or tampering with a container. 
         [0020]    In a feature of the invention, the sensor comprises an accelerometer. 
         [0021]    In a feature of the invention, the sensor detects data regarding the security, integrity, configuration, condition, disposition, orientation, location, contents, or surroundings of a container. 
         [0022]    In a feature of the invention, a first of the at least one remote sensor interfaces receives the sensor data directly from the sensor, and the gateway receives data related to the sensor data directly from a second of the at least one remote sensor interfaces different from the first of the at least one remote sensor interfaces. 
         [0023]    In a feature of the invention, the network further includes a railroad car that is monitored by the sensor. 
         [0024]    In a feature of the invention, the network further includes a tanker truck that is monitored by the sensor. 
         [0025]    In a feature of the invention, the network further includes a maritime shipping container that is monitored by the sensor. 
         [0026]    In another aspect of the invention, a method is disclosed for monitoring a container in a wireless network that includes (i) a sensor disposed for monitoring of a container, (ii) at least one remote sensor interface, and (iii) a gateway for receiving data from the at least one remote sensor interface and communicating with a network external to the wireless sensor network. The method includes the steps of (a) acquiring data related to the container; (b) after step (a), communicating sensor data as a function of the acquired data; (c) after step (b), receiving the sensor data; (d) after step (c), wirelessly transmitting data relating to the receiving sensor data; (e) after step (d), receiving data related to the sensor data; and (g) after step (e), communicating data related to the sensor data to a network external to the wireless sensor network. 
         [0027]    In a feature of this aspect, at least one common designation network is formed. 
         [0028]    Preferably, a plurality of common designation networks are be formed and comprise class-based networks. 
         [0029]    In a feature of this aspect, the method further includes supplying power to the at least one remote sensor interface utilizing solar power. Solar power may be supplied by at least one solar panel. 
         [0030]    In a feature of this aspect, the method further includes supplying power to the gateway utilizing solar power. Solar power may be supplied by at least one solar panel. 
         [0031]    In a feature of this aspect, communicating data related to the sensor data to a network external to the wireless sensor network includes communicating via a satellite radio signal. In addition thereto, or alternatively, communicating data related to the sensor data to a network external to the wireless sensor network includes communicating via a cellular telephony signal. 
         [0032]    In addition to the aforementioned aspects and features of the present invention, it should be noted that the present invention further includes the various possible combinations of such aspects and features. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]    One or more embodiments of the present invention will be described in detail with reference to the accompanying drawings which are briefly described below, and wherein the same elements are referred to with the same reference numerals. 
           [0034]      FIG. 1  is an illustration of a remote sensor interface assembly in accordance with a preferred embodiment of the present invention. 
           [0035]      FIG. 2  is an illustration of a gateway assembly in accordance with a preferred embodiment of the present invention. 
           [0036]      FIG. 3  is an illustration of the remote sensor interface assembly of  FIG. 1  and the gateway assembly of  FIG. 2  mounted on a mobile container in accordance with an exemplary scenario of HAZMAT monitoring of the present invention. 
           [0037]      FIG. 4  shows another exemplary scenario of HAZMAT monitoring in accordance with the present invention. 
           [0038]      FIG. 5  shows another exemplary scenario of HAZMAT monitoring in accordance with the present invention. 
           [0039]      FIG. 6  is an illustration of a remote sensor interface assembly and a gateway assembly, each having a respective solar power collector, in accordance with another preferred embodiment present invention. 
           [0040]      FIG. 7  shows yet another exemplary scenario of HAZMAT monitoring in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0041]    As a preliminary matter, it will readily be understood by one having ordinary skill in the relevant art (“Ordinary Artisan”) that the present invention has broad utility and application. Furthermore, any embodiment discussed and identified as being “preferred” is considered to be part of a best mode contemplated for carrying out the present invention. Other embodiments also may be discussed for additional illustrative purposes in providing a full and enabling disclosure of the present invention. Moreover, many embodiments, such as adaptations, variations, modifications, and equivalent arrangements, will be implicitly disclosed by the embodiments described herein and fall within the scope of the present invention. 
         [0042]    Accordingly, while the present invention is described herein in detail in relation to one or more embodiments, it is to be understood that this disclosure is illustrative and exemplary of the present invention, and is made merely for the purposes of providing a full and enabling disclosure of the present invention. The detailed disclosure herein of one or more embodiments is not intended, nor is to be construed, to limit the scope of patent protection afforded the present invention, which scope is to be defined by the claims and the equivalents thereof. It is not intended that the scope of patent protection afforded the present invention be defined by reading into any claim a limitation found herein that does not explicitly appear in the claim itself. 
         [0043]    Thus, for example, any sequence(s) and/or temporal order of steps of various processes or methods that are described herein are illustrative and not restrictive. Accordingly, it should be understood that, although steps of various processes or methods may be shown and described as being in a sequence or temporal order, the steps of any such processes or methods are not limited to being carried out in any particular sequence or order, absent an indication otherwise. Indeed, the steps in such processes or methods generally may be carried out in various different sequences and orders while still falling within the scope of the present invention. Accordingly, it is intended that the scope of patent protection afforded the present invention is to be defined by the appended claims rather than the description set forth herein. 
         [0044]    Additionally, it is important to note that each term used herein refers to that which the Ordinary Artisan would understand such term to mean based on the contextual use of such term herein. To the extent that the meaning of a term used herein—as understood by the Ordinary Artisan based on the contextual use of such term—differs in any way from any particular dictionary definition of such term, it is intended that the meaning of the term as understood by the Ordinary Artisan should prevail. 
         [0045]    Furthermore, it is important to note that, as used herein, “a” and “an” each generally denotes “at least one,” but does not exclude a plurality unless the contextual use dictates otherwise. Thus, reference to “a picnic basket having an apple” describes “a picnic basket having at least one apple” as well as “a picnic basket having apples.” In contrast, reference to “a picnic basket having a single apple” describes “a picnic basket having only one apple.” 
         [0046]    When used herein to join a list of items, “or” denotes “at least one of the items,” but does not exclude a plurality of items of the list. Thus, reference to “a picnic basket having cheese or crackers” describes “a picnic basket having cheese without crackers”, “a picnic basket having crackers without cheese”, and “a picnic basket having both cheese and crackers.” Finally, when used herein to join a list of items, “and” denotes “all of the items of the list.” Thus, reference to “a picnic basket having cheese and crackers” describes “a picnic basket having cheese, wherein the picnic basket further has crackers,” as well as describes “a picnic basket having crackers, wherein the picnic basket further has cheese.” 
         [0047]    Referring now to the drawings, preferred embodiments of the present invention are next described. The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0048]      FIG. 1  is a perspective view of a remote sensor interface (RSI) assembly adapted for utilization in mobile HAZMAT monitoring.  FIG. 2  is a perspective view of a gateway assembly adapted for utilization in mobile HAZMAT monitoring. In particular, the RSI assembly of  FIG. 1  includes an RSI  100  attached to a collar plate  102  for mounting to a container. The gateway assembly of  FIG. 2  includes a gateway  104  attached to a saddle plate  106  for mounting to a container. 
         [0049]      FIG. 3  is a schematic representation of a HAZMAT monitoring system in accordance with a preferred embodiment of the present invention. In  FIG. 3 , the RSI assembly and gateway assembly are each mounted to a mobile chemical container  108  for the purpose of monitoring the mobile chemical container  108 , and optionally the environment surrounding the container. The mobile container  108  is illustrated as a railroad tanker car merely for exemplary and illustrative purposes, and it should be understood that the descriptions herein relate equally as well to other types of mobile containers. 
         [0050]    As described herein, a remote sensor interface deployed in association with a mobile container collects data from one or more sensors and communicates the data (directly or indirectly through other RSIs) to a gateway. The gateway preferably receives the data collected by several RSIs and serves as a bridge between the RSIs and an external network such as a cellular telephony network, a satellite radio network, or the Internet. Thus, an interested party at a centralized location is able to receive data regarding remotely located mobile containers and is thereby informed of an event to which a response may be needed or appropriate. Interested parties may include local emergency response teams, hazardous materials response teams, government transportation authorities, highway authorities, aviation authorities, railroad authorities, military officials, law enforcement officials, and both the suppliers and intended recipients of transported materials. The incorporated materials provide further descriptions of RSIs, gateways, and networks formed thereby. While the invention described herein relates to various implementations of such RSIs, gateways, and networks, the RSIs are deployed with mobile containers in association with sensors for HAZMAT monitoring. 
         [0051]    With regard to  FIG. 3 , the RSI  100  is capable of electronic communications, preferably wireless communications, with the gateway  104 . In particular, in monitoring the container  108  and environment thereof, the RSI  100  conveys data regarding one or more sensors (not shown) to the gateway  104 . Each such sensor may be an on-board component of the RSI  100  as a part thereof, or may be external to the RSI. Insofar as sensors are external, such sensors are capable of communicating with the RSI either wirelessly or by way of cabled connections. 
         [0052]    As used herein with respect to HAZMAT monitoring, the term “sensor” relates broadly to many types of devices that are each in some way sensitive to the security, integrity, configuration, condition, disposition, orientation, location, contents, or surroundings of a container. Thus, a sensor can be a seal monitor that detects openings and closures of a container. A sensor can be an inclination monitor for detecting the overturning or tipping of a container that should be maintained in a particular orientation. A sensor can be a device or array of devices for measuring state conditions of a container or that of its contents such as temperature, volume, weight or mass, and pressure. A sensor can be any activity-monitoring or reconnaissance device such as a camera, a microphone, a motion detector, a light detector, and a broad-band RF signal scanner. A sensor can be a device for detecting physical presence, asset movement, and tampering such as a pressure-sensitive pad on a floor or surface, a switch on an access-panel, and an optical device such as an infra-red beam device, and an on-board accelerometer. 
         [0053]    Furthermore, a sensor, nominally a chemical sensor, can be a device that detects a particular chemical or substance, or detects a range of chemicals or substances. A chemical sensor can be a device that is sensitive to any presence of a chemical or substance that generally should not be present in any detectable quantity or concentration, such as a chemical weapon or biohazard. Moreover, a chemical sensor can be a device that generates a response to a raised concentration of a chemical or substance, such as carbon monoxide, that is generally otherwise present in safe, trace, or ambient concentrations. 
         [0054]      FIG. 4  is a schematic illustration of a HAZMAT monitoring system in accordance with another embodiment of the present invention. In  FIG. 4 , the RSI  100  and the gateway  104  are each mounted on the mobile container  108  that contains a potentially hazardous chemical. Several sensors  110  are attached to the mobile container  108  proximal a manifold of valves and vents. A HAZMAT related event is occurring in that a particular sensor  110 ′ detects the potentially hazardous chemical in the form of a gas  112  escaping from the container, and the sensor  110 ′ consequently transmits an RF signal  114  to the RSI  100 . In response to receipt of the signal  114 , the RSI  100  transmits an RF signal  116  to the gateway  104 . In response to receipt of the signal  116 , the gateway  104  communicates information regarding the escaping gas  112  via satellite communications  118  and/or cellular communications  122 . In this respect, the gateway  104  communicates via satellite communications  118  with satellite  120  and/or communicates via cellular communications  122  with tower  124 . Cellular communications preferably are used when a cell tower is within range of the gateway, and satellite communications preferably are used when cellular communications are unavailable to the gateway. The information conveyed by communications  118 , 122  is further carried by respective external networks, of which the satellite  120  and tower  124  are parts, to one or more parties that are interested in the escaping gas  112  and contents of the container  108 . Such external networks may comprise, for example, the Internet. 
         [0055]    In variations of the exemplary system of  FIG. 4 , wireless signals transmitted by a gateway are received by an antenna in a proprietary wireless network such as that at a controlled private facility. In another example, according to the present invention, a gateway transmits a satellite radio signal but not a cellular telephony signal, and, in yet another example, a gateway transmits a cellular telephony signal but not a satellite radio signal. 
         [0056]      FIG. 5  is a schematic illustration of a HAZMAT monitoring system in accordance with still yet another embodiment of the present invention.  FIG. 5  illustrates that a gateway is preferably deployed with a number of RSIs, and that a network is formed among the RSIs and gateway. Within such a network, which may be a common designation network and/or an ad hoc network, wireless signals can be relayed from RSI to RSI (i.e., the network includes “hopping” of communications from RSI to RSI), and a gateway can receive data from a particular RSI by way of one or more other RSIs that relay the data, wherein the particular RSI otherwise is out of range of the gateway. 
         [0057]    A train of railroad cars proceeding along a track includes a first mobile container  140  having mounted thereon a first RSI  142 , a second mobile container  144  having mounted thereon a second RSI  146 , and a third mobile container  148  having mounted thereon a gateway  150 . A HAZMAT related event is occurring in that a substance  151  leaking from the first mobile container  140  is detected by one or more chemical sensors proximal or on-board the first RSI  142 . The first RSI  142  transmits a wireless signal  152  that conveys data related to the detection of the leaking substance  151 . Responsively to its receipt of the wireless signal  152 , the second RSI  146  transmits a wireless signal  154  that, among other things, relays the data related to the detection of the leaking substance to the gateway  150 . In response to its receipt of the signal  154 , the gateway  150  communicates information regarding the detection of the leaking substance via the satellite communications  156  and/or the cellular communications  158  for further propagation of the information regarding the detection of the leak by way of networks associated respectively with the Earth orbiting satellite  160  and/or cell tower  162 . 
         [0058]      FIG. 6  is a schematic illustration of a HAZMAT monitoring system in accordance with a preferred embodiment of the present invention wherein solar power collectors are utilized to provide power. An RSI  170  and gateway  172  have attached thereto respective solar power collectors  174 ,  176 . The solar power collectors serve to re-charge, supplement, or obviate electrical batteries that might otherwise be drained causing RSIs and gateways to lose function. The solar power collectors thereby serve to reduce costs related to replacing spent batteries as well as serving to extend the potential range of RSI and gateway networks into areas where battery servicing is infeasible according to costs, according to needs for secrecy, or according to the presence of hazards posed by materials, conditions, or even hostile forces. Sensors associated with RSIs may also be powered in part or solely by solar power collectors. In yet other variations, one or more sensors may be powered by solar power collectors while the RSIs and/or gateways are powered by internal power sources such as batteries. Moreover, when internal power sources are utilized, the RSIs and/or gateways preferably reside in “standby” or “sleep mode” until awoken in accordance with one or more of the incorporated references. 
         [0059]      FIG. 7  is a schematic illustration of a HAZMAT monitoring system in accordance with another embodiment of the present invention. Several common designation networks, which may include a class-based network, are formed among common designations of mobile containers. An RSI  202  mounted on mobile container  204 , which RSI  202  is out of range of the gateway  214 , has formed a first “radioactive” common designation network with an RSI  206  mounted on mobile container  208 . A HAZMAT related event has occurred within the network in that a radiation sensor on-board or proximal the RSI  202  has detected a raised radiation level at the surface of the mobile container  204 . Such an event may indicate, for example, that radioactive material is leaking, that tampering is occurring, or that undesired shifting of materials or shielding has occurred within the mobile container  204 . A wireless signal  210  is transmitted by the RSI  202  and is received by the RSI  206 . The wireless signal  210  conveys data related to the event from the RSI  202  to the RSI  206 . Responsively to its receipt of the signal  210 , the RSI  206  transmits a wireless signal  212  to a stationary gateway  214 , thereby relaying data related to the event to the gateway  214  for further communications (not shown). 
         [0060]    Furthermore, as shown in  FIG. 7 , an RSI  222  mounted on the mobile container  224 , which RSI  222  is out of range of the gateway  214 , has formed a second “chemical” common designation network with an RSI  226  mounted on the mobile container  228 . A HAZMAT related event has occurred within the network in that a chemical sensor on-board or proximal the RSI  222  has detected a raised concentration of a gaseous substance at the valve manifold area of the mobile container  224 . Such an event may indicate, for example, that a valve or the container  224  is leaking or that tampering is occurring. A wireless signal  230  is transmitted by the RSI  222  and is received by the RSI  226 . The wireless signal  230  conveys data related to the event from the RSI  222  to the RSI  226 . Responsively to its receipt of the signal  230 , the RSI  226  transmits a wireless signal  232  to the stationary gateway  214 , thereby relaying data related to the event to the gateway  214  for further communications (not shown). 
         [0061]    Still yet, as shown in  FIG. 7 , an RSI  242  mounted on the mobile container  244 , which RSI  242  is out of range of the gateway  214 , has formed a third “bio-chemical” common designation network with an RSI  246  mounted on the mobile container  248 . A HAZMAT related event has occurred within the network in that a motion sensor, an accelerometer, or a proximity sensor associated with the RSI  242  has detected unauthorized movement of the mobile container  244  that contains a material that represents a potential bio-chemical hazard. Such an event may indicate, for example, that theft is occurring or that the mobile container  244  is being moved in error. A wireless signal  250  is transmitted by the RSI  242  and is received by the RSI  246 . The wireless signal  250  conveys data related to the event from RSI  242  to RSI  246 . Responsively to its receipt of the signal  250 , the RSI  246  transmits a wireless signal  260  to the stationary gateway  214 , thereby relaying data related to the event to the gateway  214  for further communications (not shown). 
         [0062]    As will be appreciated from the foregoing description related to  FIG. 7 , communications within the radioactive network do not result in communications within any of the chemical and bio-chemical networks, and vice-versa. This results from the preferred use of common designation ad hoc networks within the HAZMAT monitoring system. Communications between RSIs and gateways further may be deterministic or nondeterministic. 
         [0063]    Several HAZMAT monitoring systems described herein with reference to the figures relate to chemical sensors for monitoring transported or stored chemicals and substances. Such monitoring relates to work-place safety, public health, and the protection of the environment in that many chemicals and substances are indeed hazardous if released or mishandled. Furthermore, such monitoring also relates to antiterrorism activities, as such chemicals and substances can be used in terrorist attacks. It is therefore to be understood that, though particular substances are named for exemplary purposes, the scenarios discussed herein relate particularly to any hazardous material, such as those that represent chemical, biological, radiological, nuclear, and explosive threats. Moreover, insofar as such materials represent commercially valuable assets, it should be understood that such monitoring also broadly relates to asset monitoring and asset protection in general without regard for whether such assets are hazardous, in that many chemicals and substances can be extremely valuable in various industries. 
         [0064]    Particular chemicals and sensors thereof to which descriptions herein relate include, but are not limited to, carbon monoxide, hydrogen sulfide, nitrogen dioxide, nitric oxide, chlorine, oxygen, sulfur dioxide, hydrogen, and other materials useful in various industries or produced as by-products thereof. Other examples include combustible materials such as methane, butane, propane, n-pentane, acetylene, hexamethyldisilazane (HMDS), petroleum, and petroleum distillates. 
         [0065]    It will further be appreciated that each of the aforementioned exemplary scenarios involves detection of a leaking substance, escaping gas, or other “event” relating to a container that is monitored, and that the resulting communications are typically for purposes of alerting the appropriate person or entity for an appropriate response. 
         [0066]    It also will be appreciated that each of the aforementioned exemplary scenarios involves outdoor HAZMAT monitoring but that the HAZMAT monitoring in accordance with the present invention likewise may be utilized indoors or both indoors and outdoors. 
         [0067]    Event-driven monitoring as further contemplated herein, however, may include proactive monitoring in addition to such reactive monitoring. For example, if a sensor comprises a camera, proactive monitoring may include reviewing still pictures or video clips periodically captured by the camera to insure nothing out of the ordinary is occurring with regard to the container. A sensor further may include a GPS receiver, whereby the location of the container can be remotely tracked at periodic intervals to insure that the location of the container is within expected limits. Such proactive monitoring may include acquiring data via one or more sensors at predetermined intervals using a timer disposed either at the sensor or at an RSI associated with the sensor. Alternatively, such proactive monitoring may include acquiring data via one or more sensors in response to queries or commands that are issued from the external network via a gateway to one or more RSIs and associated sensor(s). Such queries or commands could be sent at predetermined intervals, in response to predetermined trigger events, or on demand of a user. Moreover, communications from a gateway to another gateway (such as a mobile gateway) and/or an RSI from which sensor-acquired information is desired preferably may be effected using common designation networking in order to reduce RF interference and unnecessary power consumption by other communication devices in the area. 
         [0068]    Finally, in order to reduce power consumption and prolong battery life, wake-up technology preferably is utilized in the RSIs and gateways (especially mobile gateways) in the HAZMAT monitoring systems in accordance with the present invention. Such wake-up technology is disclosed, for example, in U.S. Patent Application Publication No. 2005/0093703 Al (titled “Systems and Methods Having LPRF Device Wake Up Using Wireless Tag”) and U.S. patent application Ser. No. 11/422,321 (titled “Remote Sensor Interface (RSI) Stepped Wake-Up Sequence”), which published as U.S. Patent Application Publication No. 2006/0276161 A1, both disclosures of which have been incorporated herein by reference. Such wake-up technology preferably is used not only in RSIs but also in gateways and, in particular, in mobile gateways. Such use of the wake-up technology not only provides reduced power consumption and prolongs internal power sources of these communications devices, but further provides a stealth advantage/security feature in which these communication devices may only respond (and thus reveal their presence) upon receipt of an appropriate wake-up signal. 
         [0069]    Based on the foregoing description, it will be readily understood by those persons skilled in the art that the present invention is susceptible of broad utility and application. Many embodiments and adaptations of the present invention other than those specifically described herein, as well as many variations, modifications, and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing descriptions thereof, without departing from the substance or scope of the present invention. 
         [0070]    Accordingly, while the present invention has been described herein in detail in relation to one or more preferred embodiments, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for the purpose of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended to be construed to limit the present invention or otherwise exclude any such other embodiments, adaptations, variations, modifications or equivalent arrangements, the present invention being limited only by the claims appended hereto and the equivalents thereof.