阅读说明：本技术 一种周界入侵检测方法 (Perimeter intrusion detection method ) 是由 方志军 于 2021-06-28 设计创作，主要内容包括：本发明公开一种周界入侵检测方法,包括：基于深度学习算法获取覆盖周界区域的监控视频图像中的运动对象的实体类型、二维坐标和行为类型；根据所述二维坐标获取该对象的三维坐标；根据所述三维坐标获取该对象与警戒区和缓冲区的位置关系；根据该位置关系、所述实体类型、所述行为类型和视频报警策略判断运动对象是否符合预警或告警规则；检测部署于周界区域的集成式周界入侵检测系统是否发出预警或告警信息,若是,对相应运动对象的坐标进行适应性转换；当运动对象符合预警或告警规则,和/或检测到预警或告警信息时,基于贝叶斯决策算法判断运动对象是否为入侵对象,若是,对外预警或告警。根据本发明,能解决现有周界防范技术的误报率高的问题。(The invention discloses a perimeter intrusion detection method, which comprises the following steps: acquiring an entity type, a two-dimensional coordinate and a behavior type of a moving object in a monitoring video image covering a perimeter region based on a deep learning algorithm; acquiring a three-dimensional coordinate of the object according to the two-dimensional coordinate; acquiring the position relation between the object and the warning area and the buffer area according to the three-dimensional coordinates; judging whether the moving object meets an early warning or warning rule or not according to the position relation, the entity type, the behavior type and a video warning strategy; detecting whether an integrated perimeter intrusion detection system deployed in a perimeter area sends out early warning or alarm information or not, and if so, performing adaptive conversion on coordinates of corresponding moving objects; and when the moving object accords with an early warning or warning rule and/or early warning or warning information is detected, judging whether the moving object is an invading object or not based on a Bayesian decision algorithm, and if so, early warning or warning the moving object outwards. According to the invention, the problem of high false alarm rate of the existing perimeter precaution technology can be solved.)

1. A perimeter intrusion detection method, comprising:

adopting a preset deep learning algorithm to identify a moving object in a monitoring video image covering a perimeter region, and acquiring an entity type, two-dimensional coordinate data and a behavior type of the moving object;

acquiring three-dimensional coordinate data of the moving object according to the two-dimensional coordinate data of the moving object;

acquiring the position relation between the moving object and a preset warning area and a preset buffer area according to the three-dimensional coordinate data of the moving object;

judging whether the moving object meets a preset early warning rule or a preset alarm rule or not according to the position relation between the moving object and the warning area and the buffer area, the entity type and the behavior type of the moving object and a preset video alarm strategy;

detecting whether an integrated perimeter intrusion detection system based on multiple sensors and deployed in the perimeter area sends out early warning information or not, if so, converting coordinate data of a moving object contained in the early warning information or the warning information into coordinate data under a coordinate system corresponding to the three-dimensional coordinate data;

and when the moving object accords with the early warning rule or the warning rule and/or the early warning information or the warning information is detected, judging whether the moving object is an invading object or not based on a Bayesian decision algorithm, and if so, early warning or warning the moving object outwards.

2. The perimeter intrusion detection method according to claim 1, wherein the deep learning algorithm is the fast R-CNN algorithm;

the entity types include vehicles, pedestrians, animals, trees, and shadows;

the types of behaviors include loitering, running, climbing, and alarming.

3. The perimeter intrusion detection method according to claim 2, wherein the acquiring three-dimensional coordinate data of the moving object from the two-dimensional coordinate data of the moving object comprises:

acquiring a monitoring video image covering the perimeter area;

projecting the monitoring video image to a corresponding three-dimensional space covering the perimeter region to obtain a first mapping transformation matrix;

and acquiring three-dimensional coordinate data of the moving object based on the first mapping transformation matrix and the two-dimensional coordinate data of the moving object.

4. The perimeter intrusion detection method according to claim 3, wherein the alert zone is circumferentially disposed at the perimeter region with a predetermined first width, and the buffer zone is circumferentially disposed at the alert zone with a predetermined second width.

5. The perimeter intrusion detection method according to claim 4, wherein the video alarm policies include the early warning rules, the no-early warning rules and the alarm rules;

the early warning rule comprises the following steps: when a moving object with a preset entity type enters the buffer area from a preset safety area, sending early warning information, wherein the early warning information comprises the entity type and the behavior type of the moving object;

the pre-warning-free rule comprises the following steps: when the moving object of the preset type belongs to a preset warning-free object, warning information is not sent out;

the alarm rule comprises: and when the moving object with the preset entity type enters the warning area from the buffer area, sending out warning information, wherein the warning information comprises the entity type and the behavior type of the moving object.

6. The perimeter intrusion detection method according to claim 5, wherein the early warning rules further comprise:

when the staying time of the moving object in the buffer zone exceeds a preset first staying time threshold value, sending out early warning information;

when the moving object moves from the buffer area to a preset safety area, sending out early warning information;

the alarm rule further comprises:

when the staying time of the moving object in the warning area exceeds a preset second staying time threshold value, sending out warning information;

and when the moving object moves from the warning area to the buffer area, sending out alarm information.

7. The perimeter intrusion detection method according to claim 6, wherein the integrated perimeter intrusion detection system based on multiple sensors comprises a perimeter intrusion detection subsystem based on a vibrating optical fiber sensor, a perimeter intrusion detection subsystem based on a leaky cable sensor, a perimeter intrusion detection subsystem based on a laser correlation sensor, a perimeter intrusion detection subsystem based on an infrared correlation sensor, and a perimeter intrusion detection subsystem based on an electronic fence;

the perimeter area is divided into five sub-areas, and each perimeter intrusion detection subsystem is respectively deployed in the corresponding sub-area.

8. The perimeter intrusion detection method according to claim 6, wherein the converting the coordinate data of the moving object included in the warning information or the warning information into the coordinate data in the coordinate system corresponding to the three-dimensional coordinate data includes:

mapping a coordinate system corresponding to the integrated perimeter intrusion detection system to a coordinate system corresponding to the three-dimensional coordinate data to obtain a second mapping transformation matrix;

and acquiring coordinate data of the moving object in a coordinate system corresponding to the three-dimensional coordinate data based on the second mapping transformation matrix and the coordinate data of the moving object.

9. The perimeter intrusion detection method according to claim 7, wherein the external warning or alarm comprises:

and acquiring a monitoring video image covering the moving object, identifying the moving object in the monitoring video image in a color distinguishing mode, and tracking and predicting the moving object by adopting a Kalman filtering algorithm until the moving object leaves a monitoring range.

10. The perimeter intrusion detection method according to claim 9, further comprising, after the external warning or alarm:

and rechecking corresponding early warning information or alarm information, and optimizing the deep learning algorithm and/or the integrated perimeter intrusion detection system based on a rechecking result in a preset time period.

Technical Field

The invention belongs to the field of perimeter precaution, and particularly relates to a perimeter intrusion detection method.

Background

With the development and progress of society, the security monitoring and prevention problem of the perimeter is more and more paid attention by people. The perimeter precaution is the most basic system in public safety precaution, is the first line of defense for preventing illegal intrusion and abnormal events, is also a very important line of defense, and makes due contribution to social security guarantee.

The existing perimeter precaution technologies mainly comprise infrared correlation, laser detection, electronic fences, video shooting, optical fiber sensing and the like, and the perimeter precaution technologies are widely applied in respective applicable scenes, but are limited by factors such as objective technical conditions and the like, so that the perimeter precaution technologies have respective problems and defects in the aspects of monitoring principle, monitoring capability, environmental factor interference resistance, false alarm and missed alarm rate and the like.

In practical application, the perimeter precaution technology mainly has the problem of high false alarm rate, for example, a large amount of alarms are often triggered under the condition that internal and external personnel normally move inside and outside the perimeter, alarms are also triggered under the conditions of abnormal weather and tree shaking beside the perimeter, and the like, so that the workload of alarm confirmation is overlarge, the workers often cannot handle the alarms, further the real alarm event is submerged by various false alarms, and the practical effect of perimeter precaution is poor.

Disclosure of Invention

The invention aims to solve the problem of high false alarm rate of the existing perimeter precaution technology.

In order to achieve the above object, the present invention provides a perimeter intrusion detection method, including the steps of:

adopting a preset deep learning algorithm to identify a moving object in a monitoring video image covering a perimeter region, and acquiring an entity type, two-dimensional coordinate data and a behavior type of the moving object;

acquiring three-dimensional coordinate data of the moving object according to the two-dimensional coordinate data of the moving object;

acquiring the position relation between the moving object and a preset warning area and a preset buffer area according to the three-dimensional coordinate data of the moving object;

judging whether the moving object meets a preset early warning rule or a preset alarm rule or not according to the position relation between the moving object and the warning area and the buffer area, the entity type and the behavior type of the moving object and a preset video alarm strategy;

detecting whether an integrated perimeter intrusion detection system based on multiple sensors and deployed in the perimeter area sends out early warning information or not, if so, converting coordinate data of a moving object contained in the early warning information or the warning information into coordinate data under a coordinate system corresponding to the three-dimensional coordinate data;

and when the moving object accords with the early warning rule or the warning rule and/or the early warning information or the warning information is detected, judging whether the moving object is an invading object or not based on a Bayesian decision algorithm, and if so, early warning or warning the moving object outwards.

Preferably, the deep learning algorithm is a Faster R-CNN algorithm;

the entity types include vehicles, pedestrians, animals, trees, and shadows;

the types of behaviors include loitering, running, climbing, and alarming.

Preferably, the acquiring three-dimensional coordinate data of the moving object from two-dimensional coordinate data of the moving object includes:

acquiring a monitoring video image covering the perimeter area;

projecting the monitoring video image to a corresponding three-dimensional space covering the perimeter region to obtain a first mapping transformation matrix;

and acquiring three-dimensional coordinate data of the moving object based on the first mapping transformation matrix and the two-dimensional coordinate data of the moving object.

Preferably, the warning region is circumferentially disposed in the perimeter region with a predetermined first width, and the buffer region is circumferentially disposed in the warning region with a predetermined second width.

Preferably, the video alarm policy includes the early warning rule, the warning-free rule and an alarm rule;

the early warning rule comprises the following steps: when a moving object with a preset entity type enters the buffer area from a preset safety area, sending early warning information, wherein the early warning information comprises the entity type and the behavior type of the moving object;

the pre-warning-free rule comprises the following steps: when the moving object of the preset type belongs to a preset warning-free object, warning information is not sent out;

the alarm rule comprises: and when the moving object with the preset entity type enters the warning area from the buffer area, sending out warning information, wherein the warning information comprises the entity type and the behavior type of the moving object.

Preferably, the early warning rule further includes:

when the staying time of the moving object in the buffer zone exceeds a preset first staying time threshold value, sending out early warning information;

when the moving object moves from the buffer area to a preset safety area, sending out early warning information;

the alarm rule further comprises:

when the staying time of the moving object in the warning area exceeds a preset second staying time threshold value, sending out warning information;

and when the moving object moves from the warning area to the buffer area, sending out alarm information.

Preferably, the multi-sensor based integrated perimeter intrusion detection system comprises a perimeter intrusion detection subsystem based on a vibrating optical fiber sensor, a perimeter intrusion detection subsystem based on a leaky cable sensor, a perimeter intrusion detection subsystem based on a laser correlation sensor, a perimeter intrusion detection subsystem based on an infrared correlation sensor and a perimeter intrusion detection subsystem based on an electronic fence;

the perimeter area is divided into five sub-areas, and each perimeter intrusion detection subsystem is respectively deployed in the corresponding sub-area.

Preferably, the converting the coordinate data of the moving object included in the warning information or the warning information into the coordinate data in the coordinate system corresponding to the three-dimensional coordinate data includes:

mapping a coordinate system corresponding to the integrated perimeter intrusion detection system to a coordinate system corresponding to the three-dimensional coordinate data to obtain a second mapping transformation matrix;

and acquiring coordinate data of the moving object in a coordinate system corresponding to the three-dimensional coordinate data based on the second mapping transformation matrix and the coordinate data of the moving object.

Preferably, the external warning or alarm includes:

and acquiring a monitoring video image covering the moving object, identifying the moving object in the monitoring video image in a color distinguishing mode, and tracking and predicting the moving object by adopting a Kalman filtering algorithm until the moving object leaves a monitoring range.

Preferably, after the external warning or alarm, the method further includes:

and rechecking corresponding early warning information or alarm information, and optimizing the deep learning algorithm and/or the integrated perimeter intrusion detection system based on a rechecking result in a preset time period.

The invention has the beneficial effects that:

the perimeter intrusion detection method comprises the steps of firstly, adopting a preset deep learning algorithm to identify a moving object in a monitoring video image covering a perimeter area, and acquiring an entity type, two-dimensional coordinate data and a behavior type of the moving object; secondly, acquiring three-dimensional coordinate data of the moving object according to the two-dimensional coordinate data of the moving object; thirdly, acquiring the position relation between the moving object and a preset warning area and a preset buffer area according to the three-dimensional coordinate data of the moving object; fourthly, judging whether the moving object accords with a preset early warning rule or a preset alarm rule according to the position relation between the moving object and the warning area and the buffer area, the entity type and the behavior type of the moving object and a preset video alarm strategy; fifthly, detecting whether an integrated perimeter intrusion detection system based on multiple sensors and pre-deployed in the perimeter area sends out early warning information or warning information, if so, converting coordinate data of a moving object contained in the early warning information or the warning information into coordinate data under a coordinate system corresponding to the three-dimensional coordinate data; and finally, when the moving object accords with the early warning rule or the warning rule and/or the early warning information or the warning information is detected, judging whether the moving object is an invading object or not based on a Bayesian decision algorithm, and if so, early warning or warning the moving object outwards.

The perimeter intrusion detection method of the invention is based on the intelligent analysis of the monitoring video image covering the perimeter area to obtain a plurality of moving objects in the defense area; then acquiring abnormal data monitored by the integrated perimeter intrusion detection system based on the multiple sensors through an open interface; and then, overlapping the acquired abnormal data on an intelligent video analysis result, and carrying out intrusion judgment by adopting a Bayesian decision algorithm. Therefore, compared with the existing perimeter precaution technology, the perimeter intrusion detection method disclosed by the invention has the advantages that the target is identified more accurately, the intrusion behavior is judged more intelligently, the false alarm rate is lower, and the problem of higher false alarm rate of the existing perimeter precaution technology can be effectively solved.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.

FIG. 1 is a flow chart showing an implementation of a perimeter intrusion detection method according to an embodiment of the present invention.

Detailed Description

Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Example (b): fig. 1 shows a flowchart of an implementation of a perimeter intrusion detection method according to an embodiment of the present invention.

Referring to fig. 1, a perimeter intrusion detection method according to an embodiment of the present invention includes the following steps:

adopting a preset deep learning algorithm to identify a moving object in a monitoring video image covering a perimeter region, and acquiring an entity type, two-dimensional coordinate data and a behavior type of the moving object;

acquiring three-dimensional coordinate data of the moving object according to the two-dimensional coordinate data of the moving object;

acquiring the position relation between the moving object and a preset warning area and a preset buffer area according to the three-dimensional coordinate data of the moving object;

judging whether the moving object meets a preset early warning rule or a preset alarm rule or not according to the position relation between the moving object and the warning area and the buffer area, the entity type and the behavior type of the moving object and a preset video alarm strategy;

detecting whether an integrated perimeter intrusion detection system based on multiple sensors and deployed in the perimeter area sends out early warning information or not, if so, converting coordinate data of a moving object contained in the early warning information or the warning information into coordinate data under a coordinate system corresponding to the three-dimensional coordinate data;

and when the moving object accords with the early warning rule or the warning rule and/or the early warning information or the warning information is detected, judging whether the moving object is an invading object or not based on a Bayesian decision algorithm, and if so, early warning or warning the moving object outwards.

Specifically, in the embodiment of the invention, the interface is adapted to and connected with various products for perimeter precaution, and the real-time video stream of the video monitoring equipment is acquired through a national standard protocol.

Further, in the embodiment of the invention, the deep learning algorithm is a Faster R-CNN algorithm;

the entity types include vehicles, pedestrians, animals, trees, and shadows;

the types of behaviors include loitering, running, climbing, and alarming.

Specifically, in the embodiment of the present invention, an enhanced region-based convolutional neural network algorithm (fast R-CNN) is adopted to perform real-time processing on a surveillance video image covering a perimeter region: the method comprises the steps of carrying out target segmentation and target identification on objects in a monitored video image, accurately identifying entity types such as vehicles, pedestrians, animals, trees, light shadows and the like in the monitored video image, simultaneously obtaining image coordinate information of each target object, and judging behavior types of the target objects such as loitering, running, climbing, alarming and the like according to object continuous change forms of continuous multi-frame pictures in a video stream.

Still further, in an embodiment of the present invention, the acquiring three-dimensional coordinate data of the moving object according to the two-dimensional coordinate data of the moving object includes:

acquiring a monitoring video image covering the perimeter area;

projecting the monitoring video image to a corresponding three-dimensional space covering the perimeter region to obtain a first mapping transformation matrix;

and acquiring three-dimensional coordinate data of the moving object based on the first mapping transformation matrix and the two-dimensional coordinate data of the moving object.

Specifically, in the embodiment of the present invention, a monitoring video image covering the perimeter area is acquired in real time, and the monitoring video image is mapped with a corresponding three-dimensional space covering the perimeter area, so as to obtain a coordinate transformation projection matrix, that is, a first mapping transformation matrix, of a two-dimensional coordinate of an image feature point in the monitoring video image and a three-dimensional coordinate of a three-dimensional feature point in the three-dimensional space.

Still further, in the embodiment of the present invention, the warning region is disposed around the perimeter region with a predetermined first width, and the buffer region is disposed around the warning region with a predetermined second width.

Still further, in the embodiment of the present invention, the video alarm policy includes the early warning rule, the early warning exempting rule, and an alarm rule;

the early warning rule comprises the following steps: when a moving object with a preset entity type enters the buffer area from a preset safety area, sending early warning information, wherein the early warning information comprises the entity type and the behavior type of the moving object;

the pre-warning-free rule comprises the following steps: when the moving object of the preset type belongs to a preset warning-free object, warning information is not sent out;

the alarm rule comprises: and when the moving object with the preset entity type enters the warning area from the buffer area, sending out warning information, wherein the warning information comprises the entity type and the behavior type of the moving object.

Still further, in the embodiment of the present invention, the early warning rule further includes:

when the staying time of the moving object in the buffer zone exceeds a preset first staying time threshold value, sending out early warning information;

when the moving object moves from the buffer area to a preset safety area, sending out early warning information;

the alarm rule further comprises:

when the staying time of the moving object in the warning area exceeds a preset second staying time threshold value, sending out warning information;

and when the moving object moves from the warning area to the buffer area, sending out alarm information.

Specifically, in the embodiment of the present invention, when the moving object meets the early warning rule or the warning rule, the moving object is recorded. Setting a buffer area for the areas where the target objects are far away from the perimeter boundary line and need to be continuously concerned, carrying out early warning when the target objects enter the buffer area, and simultaneously setting an early warning free rule to directly filter part of the target objects so as to reduce the early warning amount; the distance is very close to the boundary or the important area is set as a warning area, and the intrusion alarm is directly triggered when the distance enters the area.

In the embodiment of the invention, the early warning-free rule is arranged in the buffer area, only the ordinary moving target is early warned, and the moving target in the early warning-free rule can be directly filtered, such as a worker wearing a specific work clothes.

Still further, in the embodiment of the present invention, the integrated perimeter intrusion detection system based on multiple sensors includes a perimeter intrusion detection subsystem based on a vibrating optical fiber sensor, a perimeter intrusion detection subsystem based on a leaking cable sensor, a perimeter intrusion detection subsystem based on a laser correlation sensor, a perimeter intrusion detection subsystem based on an infrared correlation sensor, and a perimeter intrusion detection subsystem based on an electronic fence;

the perimeter area is divided into five sub-areas, and each perimeter intrusion detection subsystem is respectively deployed in the corresponding sub-area.

Specifically, in the embodiment of the invention, the perimeter area is divided into a plurality of defense areas for parallel processing, each defense area independently analyzes signals and independently operates, and when people invade from different defense areas at the same time, the invaded defense areas can simultaneously alarm and do not influence each other. Each defense area can independently set intrusion judgment parameters according to different environments of the defense area, such as sensitivity adjustment of a single defense area, and alarm parameters such as sensitivity of each defense area can be independently adjusted to adapt to different peripheral environments, such as weather change, animal activities, vehicles of nearby roads and the like.

Still further, in the embodiment of the present invention, the converting the coordinate data of the moving object included in the warning information or the warning information into the coordinate data in the coordinate system corresponding to the three-dimensional coordinate data includes:

mapping a coordinate system corresponding to the integrated perimeter intrusion detection system to a coordinate system corresponding to the three-dimensional coordinate data to obtain a second mapping transformation matrix;

and acquiring coordinate data of the moving object in a coordinate system corresponding to the three-dimensional coordinate data based on the second mapping transformation matrix and the coordinate data of the moving object.

Specifically, in the embodiment of the present invention, current monitoring data of the integrated perimeter intrusion detection system is actively obtained or passively received to detect whether there is an early warning event or an alarm event, and when there is an early warning event or an alarm event, an early warning type or an alarm type, coordinate data of a target object, an entity type of the target object, and other related information are obtained.

Still further, in the embodiment of the present invention, the external warning or alarm includes:

and acquiring a monitoring video image covering the moving object, identifying the moving object in the monitoring video image in a color distinguishing mode, and tracking and predicting the moving object by adopting a Kalman filtering algorithm until the moving object leaves a monitoring range.

Specifically, in the embodiment of the present invention, for the situation that both the video analysis and the integrated perimeter intrusion detection system trigger the early warning/alarm, or the situation that the early warning/alarm is triggered unilaterally, a bayesian decision algorithm is used to perform bidirectional reference, and finally, the external disturbance type is determined, such as loitering, climbing, crossing, enclosure pressing, running or walking in an area, and mechanical construction which may threaten a perimeter building. And when the system enters a preset buffer area, the behavior has a triggering early warning of potential threat, and when the system enters an alert area or the intrusion behavior (such as crossing) in execution is confirmed, an alarm is triggered.

Still further, in the embodiment of the present invention, after the external warning or alarm, the method further includes:

rechecking corresponding early warning information or warning information;

optimizing the deep learning algorithm and/or the integrated perimeter intrusion detection system based on a rechecking result within a predetermined period of time.

Specifically, in the embodiment of the present invention, the triggered early warning/alarm information is manually rechecked and correspondingly processed, and then the processing precision of the deep learning algorithm and the continuous optimization processing precision of the integrated perimeter intrusion detection system are periodically optimized and adjusted according to the result of the manual rechecking.

The perimeter intrusion detection method of the embodiment of the invention can solve the following problems of the prior perimeter precaution technology:

firstly, the moving target type identification capability of the adjacent areas at two sides of the perimeter is not enough, the behavior analysis capability of the moving target is not enough, and the false alarm rate is higher. For example, it cannot be accurately analyzed that the moving target is a person, a vehicle, an animal or the like, and it is difficult to filter out the influence caused by tree shaking, strong wind, thunderstorm and the like; the normal behavior (e.g., running, garden routine maintenance, etc.) of the area adjacent to the perimeter fence cannot be effectively filtered out.

Secondly, the current multiple perimeter precaution technologies can only be independently deployed, effective integrated cooperation cannot be carried out, mutual advantages and shortages cannot be made up, and multi-technology and multi-level three-dimensional collaborative perimeter precaution cannot be achieved.

And thirdly, manual rechecking and processing after triggering alarm are inconvenient, and automatic identification and tracking of the target in the video monitoring interface cannot be carried out during video linkage after triggering alarm.

The perimeter intrusion detection method provided by the embodiment of the invention has the following beneficial effects:

the method comprises the steps of processing perimeter monitoring video signals in real time through a deep learning algorithm, accurately identifying the types and the invasion behaviors of moving targets on two sides of a perimeter, effectively filtering non-invasion events and reducing the false alarm rate.

And secondly, integrating with perimeter precaution technologies such as vibrating optical fibers, leaking cables, laser/infrared correlation, electronic fences and the like, adjusting the influence weight of monitoring data of two parties in real time according to the change of a scene, and more accurately judging whether the behavior of a target object belongs to the intrusion behavior through a probability decision Bayesian algorithm.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.