Block Pulse Functions And Their Applications In Control Systems.pdf
Donalvon Stilwell
The concept of coefficient shift matrix is introduced to represent delay variables in block pulse series. The optimal control of a linear delay system with quadratic performance index is then studied via block pulse functions, which convert the problems into the minimization of a quadratic form with linear algebraic equation constraints. The solution of the two-point boundary-value problem with both delay and advanced arguments is circumvented. The control variable obtained is piecewise constant.
Block pulse functions and their applications in control systems.pdf
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Application control is a security practice that blocks or restricts unauthorized applications from executing in ways that put data at risk. The control functions vary based on the business purpose of the specific application, but the main objective is to help ensure the privacy and security of data used by and transmitted between applications.
Simply put, application controls ensure proper coverage and the confidentiality, integrity, and availability of the application and its associated data. With the proper application controls, businesses and organizations greatly reduce the risks and threats associated with application usage because applications are prevented from executing if they put the network or sensitive data at risk.
Most application control solutions also allow for visibility into applications, users, and content. This is helpful for understanding the data your enterprise owns and controls, its storage locations, which users have access to it, the access points, and the data transmission process. These steps are required for data discovery and classification for risk management and regulatory compliance. Application control supports these processes and allows organizations to keep their finger on the pulse of what is happening within their network.
The continued growth of the consumer drone market presents new challenges for the aviation industry. Whether it's a careless amateur pilot or a deliberate attack, the drone threat comes in many shapes and sizes.
Counter-drone technology encompasses a wide range of solutions that allow you to detect, classify, and mitigate drones and unmanned aerial vehicles. This includes everything from camera systems and specialist drone detection radar to net guns and cyber takeover systems. This is also known as counter-UAS technology because drones are a type of unmanned aerial system.
A device that uses radio energy to detect an object. Drone detection radar or counter-UAS radar sends out a signal and uses the reflection as it bounces off an object to measure its direction and distance (position).
Most radars send their radio signal as a burst, then listen for the "echo". Almost all radars are designed NOT to pick up small targets. They're designed for large object tracking, like passenger aircraft. However, specialist counter-UAS technology includes radar that tracks smaller objects, like drones, with ease.
Pros: Long range, constant tracking, highly accurate localisation. Can handle hundreds of targets simultaneously. Can track all drones regardless of autonomous flight and visual conditions (day, night, fog, etc.)
For starters, we built IRIS specifically to track drones. Featuring 360-degree azimuth and 60-degree elevation coverage, IRIS provides early warning of approaching drones from any direction, in full 3D.
Micro-doppler radar detects speed differences within moving objects. For example, a drone's rotor. This enables IRIS to distinguish between drones and other small, fast-moving objects, like birds, reducing false alarms. It can also detect autonomous and hovering drones and track multiple targets simultaneously.
Pros:
Low-cost. Can detect (and sometimes identify) multiple drones and controllers. It's also passive, so you don't need a licence to operate. Some can triangulate drone and controller positions.
Optical sensors collect light at a range of wavelengths, including visible and infrared, as well as thermal radiation, to detect drones day and night. Recent advances in optical sensor technology have improved resolution (and thereby range) and processing power in the form of AI-powered detection, tracking, and classification.
This type of counter-UAS technology involves using a microphone or microphone array (lots of microphones) to detect the sound made by a drone and calculate its direction. Use multiple microphone arrays for rough triangulation.
Pros:
Detects all drones within the near field, including those operating autonomously (without RF emissions). Detects drones in the ground clutter where other technologies can struggle. Great gap-filler in areas outside the line-of-sight of other sensors. Highly mobile and quickly deployable. Completely passive.
This is a static, mobile, or handheld device that transmits a large amount of RF energy towards the drone, masking the controller signal. This results in one of four scenarios, depending on the drone:
However, GPS spoofers can inadvertently disrupt other systems beyond the target drone. Because of the risks, GPS spoofers are primarily used as a drone countermeasure on the battlefield. They aren't as common for civilian operations.
The EMP interferes with radio links and disrupts or even destroys the electronic circuitry inside drones (plus any other electronic device within range) due to the damaging voltage and currents it creates.
Cons:
High cost. Risk of unintentionally disrupting communications or destroying other electronic devices in the area. Can cause the drone to switch off instantly so it falls, uncontrolled, to the ground.
Cons:
As a kinetic solution, it can result in debris (depending on parachute options). Drone-deployed nets can be imprecise and have long reload times. Ground-launched nets have a short range. Drone-mounted net guns often struggle to intercept and neutralize hostile drones that fly aggressively or evasively due to inertia.
Vendors:
Fortem Technologies' DroneHunter 700 supports three net gun attachments that enable it to stop drones of almost any size. Additionally, OpenWorks Engineering offers both shoulder-mounted and turret-mounted net cannons.
Cyber takeover, or cyber takedown, systems are a relatively new counter-drone technology. They passively detect radio frequency transmissions emitted by drones to identify the drone's serial number and locate the pilot's position using AI. If the operator recognises the drone as a threat, they can send a signal to hack the drone, assume control, and direct it to a safe location.
Pros:
Precise, with a low risk of collateral damage. Lightweight and configurable for both static and mobile applications. Automatically captures incident data vital for forensic investigation. Effective against both piloted and autonomous drones.
Talking about software, command and control (C2) software can make or break your counter-drone system. You must collect, process, and display data from all those different sensors and technologies in an actionable, user-friendly way.
C2 systems vary significantly in terms of capability and cost. The complexity of the connected sensors and effectors, the type of threat, and your budget influence whether you require all the bells and whistles or a more basic system. However, drone defence companies are developing industry standards for C-UAS integration, with SAPIENT's out-of-the-box data integration capabilities at the forefront.
This isn't the whole story, of course. And while data interoperability is a pre-requisite, don't underestimate the importance of other C2 functions like data fusion, workflow management, and decision support.
PWM is useful for controlling the average power or amplitude delivered by an electrical signal. The average value of voltage (and current) fed to the load is controlled by switching the supply between 0 and 100% at a rate faster than it takes the load to change significantly. The longer the switch is on, the higher the total power supplied to the load. Along with maximum power point tracking (MPPT), it is one of the primary methods of controlling the output of solar panels to that which can be utilized by a battery.[2] PWM is particularly suited for running inertial loads such as motors, which are not as easily affected by this discrete switching. The goal of PWM is to control a load; however, the PWM switching frequency must be selected carefully in order to smoothly do so.
The PWM switching frequency can vary greatly depending on load and application. For example, switching only has to be done several times a minute in an electric stove; 100 or 120 Hz (double of the utility frequency) in a lamp dimmer; between a few kilohertz (kHz) and tens of kHz for a motor drive; and well into the tens or hundreds of kHz in audio amplifiers and computer power supplies. Choosing a switching frequency that is too high for the application may cause premature failure of mechanical control components despite getting smooth control of the load. Selecting a switching frequency that is too low for the application causes oscillations in the load. The main advantage of PWM is that power loss in the switching devices is very low. When a switch is off there is practically no current, and when it is on and power is being transferred to the load, there is almost no voltage drop across the switch. Power loss, being the product of voltage and current, is thus in both cases close to zero. PWM also works well with digital controls, which, because of their on/off nature, can easily set the needed duty cycle. PWM has also been used in certain communication systems where its duty cycle has been used to convey information over a communications channel.
In electronics, many modern microcontrollers (MCUs) integrate PWM controllers exposed to external pins as peripheral devices under firmware control. These are commonly used for direct current (DC) motor control in robotics, switched-mode power supply regulation, and other applications.
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