Digital control systems offer advantages over analogue systems for medical linear accelerators. Digital systems provide higher precision through encoders and digital readouts. They are less sensitive to noise and component drift. Digital control allows remote adjustment and easy replacement of broken components. System information can be processed to monitor performance and predict problems. Overall, digital control provides improved precision and reliability compared to analogue systems.
SS9620 PV Cell Evaluation System
Overall Evaluation System Capable of Measuring
Solar Cell Dark Current
l Dark current measurement of large solar cell modules by connecting the booster unit 46015
l Precise parallel resistance measurement and bypass diode
evaluation by using the reverse polarity unit
l Maximum output power of 300W (300V/±1A, 30V/±10A)
l High speed measurement at 100 points in 5ms
l 50μs to 6s/point that supports various kinds of solar cells
l Sampling for short-pulsed, middle-pulsed and long-pulsed light
l 3-slope linear sweep function to measure finely around Isc,
Pmax and Voc
Ls catalog thiet bi tu dong gimac iv-e_dienhathe.vnDien Ha The
Khoa Học - Kỹ Thuật & Giải Trí: http://phongvan.org
Tài Liệu Khoa Học Kỹ Thuật: http://tailieukythuat.info
Thiết bị Điện Công Nghiệp - Điện Hạ Thế: http://dienhathe.org
The working principles of this project is so simple, when the water has reached the set point, then the red LED will ON and the buzzer will beeping and then the valve should be open for water to be recirculated. When the water is at a safe limit , the Green LED will ON , buzzer stops beeping and the valve should be close. Having close the pump will circulated water into the tank.
DHT11 Digital Temperature and Humidity SensorRaghav Shetty
The DHT11 Temperature & Humidity Sensor features a temperature & humidity sensor complex with calibrated digital signal output. By using the exclusive digital-signal-acquisition technique and temperature & humidity sensing technology, it ensures high reliability and excellent long term stability.
This sensor include a resistive type humidity measurement component and a NTC temperature measurement component, and connect to a high performance 8-bit microcontroller, offering excellent quality, fast response, anti-interface ability and cost effectiveness.
It’s of small size, low power consumption and up-to 20 meter signal transmission makes it a best choice for various applications.
SS9620 PV Cell Evaluation System
Overall Evaluation System Capable of Measuring
Solar Cell Dark Current
l Dark current measurement of large solar cell modules by connecting the booster unit 46015
l Precise parallel resistance measurement and bypass diode
evaluation by using the reverse polarity unit
l Maximum output power of 300W (300V/±1A, 30V/±10A)
l High speed measurement at 100 points in 5ms
l 50μs to 6s/point that supports various kinds of solar cells
l Sampling for short-pulsed, middle-pulsed and long-pulsed light
l 3-slope linear sweep function to measure finely around Isc,
Pmax and Voc
Ls catalog thiet bi tu dong gimac iv-e_dienhathe.vnDien Ha The
Khoa Học - Kỹ Thuật & Giải Trí: http://phongvan.org
Tài Liệu Khoa Học Kỹ Thuật: http://tailieukythuat.info
Thiết bị Điện Công Nghiệp - Điện Hạ Thế: http://dienhathe.org
The working principles of this project is so simple, when the water has reached the set point, then the red LED will ON and the buzzer will beeping and then the valve should be open for water to be recirculated. When the water is at a safe limit , the Green LED will ON , buzzer stops beeping and the valve should be close. Having close the pump will circulated water into the tank.
DHT11 Digital Temperature and Humidity SensorRaghav Shetty
The DHT11 Temperature & Humidity Sensor features a temperature & humidity sensor complex with calibrated digital signal output. By using the exclusive digital-signal-acquisition technique and temperature & humidity sensing technology, it ensures high reliability and excellent long term stability.
This sensor include a resistive type humidity measurement component and a NTC temperature measurement component, and connect to a high performance 8-bit microcontroller, offering excellent quality, fast response, anti-interface ability and cost effectiveness.
It’s of small size, low power consumption and up-to 20 meter signal transmission makes it a best choice for various applications.
Webinar Slides: Measurements and Analysis for Switched-mode Power Designsteledynelecroy
This webinar covers the measurements of interest for designers of switched-mode power conversion circuits and devices. With the goal of high efficient and reliable designs, we review the acquisition of voltage and current, their relationship in switched-mode power conversion circuits.
We review specific power circuit performance areas including the analysis of power device switching losses, conduction losses, dynamic on-resistance, control loop response, power quality, conducted emissions, best practices for probing power circuits, and power rail integrity measurements.
Expert Accessory Dwelling Unit (ADU) Drafting ServicesResDraft
Whether you’re looking to create a guest house, a rental unit, or a private retreat, our experienced team will design a space that complements your existing home and maximizes your investment. We provide personalized, comprehensive expert accessory dwelling unit (ADU)drafting solutions tailored to your needs, ensuring a seamless process from concept to completion.
Hello everyone! I am thrilled to present my latest portfolio on LinkedIn, marking the culmination of my architectural journey thus far. Over the span of five years, I've been fortunate to acquire a wealth of knowledge under the guidance of esteemed professors and industry mentors. From rigorous academic pursuits to practical engagements, each experience has contributed to my growth and refinement as an architecture student. This portfolio not only showcases my projects but also underscores my attention to detail and to innovative architecture as a profession.
7 Alternatives to Bullet Points in PowerPointAlvis Oh
So you tried all the ways to beautify your bullet points on your pitch deck but it just got way uglier. These points are supposed to be memorable and leave a lasting impression on your audience. With these tips, you'll no longer have to spend so much time thinking how you should present your pointers.
Can AI do good? at 'offtheCanvas' India HCI preludeAlan Dix
Invited talk at 'offtheCanvas' IndiaHCI prelude, 29th June 2024.
https://www.alandix.com/academic/talks/offtheCanvas-IndiaHCI2024/
The world is being changed fundamentally by AI and we are constantly faced with newspaper headlines about its harmful effects. However, there is also the potential to both ameliorate theses harms and use the new abilities of AI to transform society for the good. Can you make the difference?
Unleash Your Inner Demon with the "Let's Summon Demons" T-Shirt. Calling all fans of dark humor and edgy fashion! The "Let's Summon Demons" t-shirt is a unique way to express yourself and turn heads.
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You could be a professional graphic designer and still make mistakes. There is always the possibility of human error. On the other hand if you’re not a designer, the chances of making some common graphic design mistakes are even higher. Because you don’t know what you don’t know. That’s where this blog comes in. To make your job easier and help you create better designs, we have put together a list of common graphic design mistakes that you need to avoid.
1. Digital vs. Analogue Control
Systems
Presented at the 2011 Annual Meeting of the American College
of Medical Physics, Chattanooga, TN, May 1, 2011
Ivan A. Brezovich, PhD, Dept. of Rad Onc, Univ of Alabama at
Birmingham
Disclosure: Research supported in part by Varian Medical
Systems
2. Accelerator control systems
• Mechanical – Analogue or digital
– Gantry angle
– Collimator angle
– Jaw position
– MLC leaf position
– Couch positions (angle, vertical, long, lat)
– Internal devices (target, flattening filter, light field projector)
• Electronic – Analogue or digital
– Beam production
• Electron gun
• Rf power
• Steering coil current
• Bend magnet current
– Dosimetry system
– Ancillary systems (vacuum, temperature control, etc.)
3. Analogue transducer, analogue readout
10-turn potentiometer
+
Calibrated in deg gantry or
collimator angle, cm couch
position
−
Wiper
Resistance
wire
−
+
Vout
Vout
Single-turn potentiometer
Shaft
8. Limitations of analogue devices
• Precision of potentiometer ~ 0.1% linearity
– 0.4 mm for 40x40cm2 field
– Sensitive to small changes in wire resistance
– Degraded accuracy by use and age (brush)
– Sensitive to power supply voltage
• Reading accuracy ~ 0.2%
– Digital readout - used even in early linacs
13. “Analogue” precision transducers
• Geared potentiometers
– “Hour hand” pot goes around once
– “Minute hand” pot goes around many times
– 0.01% rotational precision readily obtained with 0.2%
accuracy pots
• Geared (dual) resolvers – same principle
14. Digital transducer: 3-bit shaft encoder
Standard binary encoding
Sector
Con-
tact 1
Con-
tact 2
Con-
tact 3 Angle
1 off off off 0° - 45°
2 off off ON 45° - 90°
3 off ON off 90° - 135°
4 off ON ON 135° - 180°
5 ON off off 180° - 225°
6 ON off ON 225° - 270°
7 ON ON off 270° - 315°
8 ON ON ON 315° - 360°
Contact 1 Contact 2 Contact 3
2 Sector 1
3
8
7
4
5
6
15. Sector
Con-
tact 1
Con-
tact 2
Con-
tact 3 Angle
1 off off off 0° - 45°
2 off off ON 45° - 90°
3 off ON ON 90° - 135°
4 off ON off 135° - 180°
5 ON ON off 180° - 225°
6 ON ON ON 225° - 270°
7 ON off ON 270° - 315°
8 ON off off 315° - 360°
3-bit shaft encoder
Gray encoding
3 2 Sector 1
Contact 1 Contact 2 Contact 3
8
4
5
6 7
19. Stepper motor – driver and encoder
Energizing coils A, B, C …. ccw rotation
Energizing coils A, C, B …. clockwise rotation
Coil A energized
A
A
B
B C
B
C
C
20. Stepper motor in 1-D water tank
Stepper motor
200 pulses/rev
Spindle
6 mm/rev
nut
21. Stepper motor in 3-D water tank
Stepper motor
with 90° turn gear
spindle nut
22. Initialization of Varian MLC
IR emitting diode
16:1 reduction gear (two 1: 4 planetary
gears in series)
DC electric motor with permanent magnet
Incremental encoder, 2 pulses per rev
Light detector
Spindle (screw), 1.5 mm/rev pitch
Origin (zero) when light at
detector reduced by 50%
60 leaves
MLCdrive
assembly
4.5cm
23. Initialization of Varian x-ray jaws
Hard stop
Collision
block
X-ray
jaw Origin (zero point) established when
Collision block hits Hard stop. Collision
detected by sudden surge of DC
current when motor stalls
DC motor
Reduction gear
Incremental
encoder
Spindle (screw)
nut
24. Control systems: Operational amplifier
Zin = ∞ Iin = 0 small input current
Zout = 0 Iout = ∞ high output current
Vout = (V+−V−)×A high amplification A → ∞
Vs+ , Vs− pos and neg power supply voltages
input pos
input inv
25. console
motor
+12V
-12V
-12V
+12V
Motor spins until voltage of
potentiometer at back of motor
matches program voltage
output
accelerator
op
amp
Program
voltage
Feedback voltage
power amp
Analogue mechanical control system
27. console
-12V
+12V
Output current increases until
feedback voltage matches program
voltage
accelerator
Op
amp
Program
voltage
Feedback voltage
Power amp
Feedback resistor
Bend magnet coils
Analogue electronic control system for energy
+
−
28. Output current adjusts until (processed)
signals from both chamber halves
become equal, i.e., beam is symmetric
Ion chamber
Op
amp
Power amp
Beam steering coils
Analogue electronic control for beam symmetry
Lower half
(toward couch)
Upper half
(toward gantry)
Balancing network
29. Computes ratio of inputs and compares
to desired ratio sent from node. Sends
correction signal to DAC
Ion chamber
Power
amp
Beam steering coils
Digital electronic control for beam symmetry
Lower half
(toward couch)
Upper half
(toward gantry)
Analogue to digital
converters
Con
troll
er
Node
Dig to anal
converter
30. Dual systems for safety of modern digital
accelerators
• Mechanical systems
– Encoder on back of drive motor + encoder on driven
object (gantry angle, couch position, etc.), agreement
monitored by computer
• Electronic systems
– Ion chamber has multiple segments, outputs
monitored by computer
– Resistance of bend magnet measured
32. Merits of digital systems
• Less sensitive to noise
• Less sensitive to component drift
• Easy return to original settings
• Easy replacement of broken components
• High precision of mechanical systems
– Flattening filter and field light projector can be
remotely adjusted
• Information readily available for processing
– Monitor machine performance to predict problems
• Cooling water flow rate monitored at many places
• Vacuum system leaks
• SF6 leaks
33. Merits of digital systems
• Take into account “second order effects”
– Flexing of image receiver arm
• Automatic tuning
– Slow changes of components
• Thyratron aging
• Waveguide resonant frequency