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An article about me in Pest Control Technology Magazine! Pretty cool huh?

There first page says:



If it’s true that what doesn’t kill you makes you stronger, the adage certainly describes this young man’s path to pest management. He turned his childhood entomophobia into a passion for insects, and that into a degree from Cornell University and a position as staff entomologist at American Pest, Fulton, Md.

“As a kid I was terrified of insects, but my parents didn’t want any of their children to have irrational fears,”  says Ramsey. “So my mom had me go to the library and check out a bunch of entomology books. Once I started reading about insects, I fell in love with them. Insects went from the focus of my macabre fears to the creatures that I’m the most passionate about.”

His early-found love for insects combined with hard work and determination fueled his lifelong educational aspirations and his career path. “At seven, I told everyone who would listen that I was going to be an entomologist,” He says. And he’s never looked back.



Education was highly valued in the Ramsey household. Both of his parents were avid readers and instilled a love of reading and learning in their children. Though initially skeptical about his growing fascination with insects, his parents supported his interest. “My parents thought it was pretty weird at first, but after they saw I was serious about it, they started to nurture it,” he says. “My mom loved the idea that I wanted to be a scientist.” 

In elementary school in Prince George’s County, Md., he attended classes for gifted students. It was there he met Kathy Hackett, a teacher whose husband happened to be an entomologist. “She told me she had never met an African American entomologist before,” Ramsey says. After recognizing his interests and his academic abilities, Hackett and her husband took him under their wings, fostering his ambition. “They became my second parents,” he says.

“They would always bring something back for me when they attended the annual Entomological Society of America convention.” A convention that he hoped to one day attend.

In high school, he left his mark. Despite distractions at what he describes as a “kind of a dangerous school,” he achieved the highest grade point average at the school, and maintained it for three years. He went on to receive…


Top 5 Pest Management Techniques by Amy from Duke University’s Phytotron Facility

Hello all, my name is Amy Eddings and I am ­­­an Assistant Horticulturist at Duke University’s biology research facility, which is known as the Phytotron. I recently met Agritecture’s Community Manager, Andrew Blume, when he came to tour our facility in North Carolina. If you’re curious about the research we do and what equipment we have, Andrew wrote this blog article recapping our activities and some of the Controlled Enivronment Agriculture (CEA) gear we have here at the Phytotron.

Andrew and I also shared an in-depth discussion on the pest management techniques that I practice here at the Phytotron. While there is a misconception out there that growing indoors means there won’t be pests, anyone who actually runs a biology research facility knows this is not the case. Here at the Phytotron, we have reduced the need to spray pesticides from up to 65 times a year down to only 2 limited sprays to limited parts of the facility last year – all using integrated pest management techniques.

Thus, Andrew requested I share some of my green methods for managing our pests. Most of these practices can be applied in many different growing settings and are not specific to research growing. I hope you find the techniques useful and thank you for your interest in my buggy profession!

1.     The number one best practice you can adapt is cleanliness!  

Cleanliness is your friend! As much as is humanly possible, keep your growing house, chamber or plot clean.  Keep pots, floors and benches clear of debris.  Pests can hide over winter and breed in this debris. When using a recirculation air system, check your filters or coils regularly for any mold or fungus.  When starting over with a new crop be sure to clean all your pots, benches, floors etc. with a greenhouse cleaner and when possible, especially if you have known pests issues in the area, use a high heat technique to “cook” the growing location.  In the Phytotron we have the ability to set temperatures to 45 degrees Celsius.  We run at this temperature for two to three days.  This usually insures no pests or pathogen survival to infect the next crop.  

Keep reading

The single-phase inverter IPM employs circuit design

A foreword

IPM (Intelligent Power Module, IPM) Fast with the switch, it is small to loss, low power dissipation, have many kinds of protection strong in function, antijamming capability, needn’t take anti-electrostatic measure, advantage such as being small in electric and electronic field increasingly extensive to employ. Take Model PM200DSA060 IPM as examples. Recommend IPM to employ the circuit design and application in the single-phase inverter.

Structure of 2 IPM

IPM is formed by high-speed, low-powered IGWT, preferred gate stage driver and protective circuit. Among them, IGBT is GTR and complex of MOSFET, driven GTR by MOSFET, therefore IPM has GTR high current density, low saturation voltage, high withstand voltage, MOSFET high input impedance, high switching frequency and advantage of the low propulsion power.

According to the internal power circuit configuration situation, IPM has polymorphic types, such as the PM200DSA060 type: IPM, for D type (inside integrates 2 IGBTs) . Their internal functional block diagrams are shown as in Fig. 1, the internal structure is shown as in Fig. 2. There is driving and protective circuit inside, have protecting, overheat protective, overcurrent protection and short circuit protection of Under Voltage Lock Out of control power supply to protect the function, IPM will output the fault signal FO when acting in any kind of protection function among them.

IPM internal circuit include signal isolating circuit, self-protection function and surging absorbing circuit of preventing the interference. In order to guarantee IPM is safe and reliable. Need oneself to design some peripheral circuit.

The outside of 3 IPM drives circuit design

The outside driving circuit of IPM is the interface between IPM internal circuit and controlling circuit, the operating efficiency, reliability and safety of the good system to forming with IPM of driving circuit of outside all have important meanings.

Can be seen by the structure chart within IPM. Device contains the driving circuit. So only offer and meet PWM signal, driving circuit power and electric spacer assembly to prevent interference of requirements of propulsion power. But. IPM requirements for the driving circuit output voltage are very strict: Drive the voltage range to be 13. 5V~16. 5V. The voltage is lower than 13. Low-voltage protection will take place in 5V. The voltage is higher than 16. 5V may damage the internal part; Drive the signal frequency to be 5Hz-20kHz, and need to adopt the electric spacer assembly. Prevent the interference: Drive power insulating voltage 2 times that of IPM interpolar reverse withstand voltage value (2Vces) at least ; The drive current reaches 19mA a 26mA; The Filtering capacitance of the Ausgang of the driving circuit can’t be too large. This is because when the parasitic capacitance exceed 100pF. Noise interference may touch off the internal driving circuit by mistake.

It is a kind of typical high reliability IPM external driving circuit scheme that Fig. 3 shows. PWM signal from controlling circuit passes R1 current limiter. And then connect the driving circuit within IPM and control the gas switching tube to work after and high-speed light-coupled isolation is enlarged, FO signal undergoes light-coupled isolation to export too. Among them the control power supply end of each gas switching tube adopts the isolated voltage regulation independently. 15V power, and connect the decouple capacitor (not draw in picture) of a 10μ F In order to filter the common mode noise. Rl chooses according to the output current of the controlling circuit. Such as producing PWM with DSP. Then the resistance-value of R1 can be 330Ω. R2 is according to IPM drive current chosen value, it should be small in order to prevent high impedance IPM from picking up the noise as much as possible on one hand. On the other hand will control IPM reliably enough again. Can be 6 in 2kΩ. Choose in 8kΩ. C1 is O among 2 ends and ground. 1μ F filter capacitor, PWM isolates the requiring tPLH10kV/ μ s of photosensitive resister, can choose HCPIA503 type, HCPIA504 type, PS204l type (NEC) Wait for the high-speed photosensitive resister, and input a O of head joint in the photosensitive resister. Decouple capacitor (not draw in picture) of 1μ. The photosensitive resister of FO output can use the photosensitive resister of low speed (such as PC817) . The internal pin function of IPM is shown in Table 1.

The outside interface circuit of Fig. 3 is fixed on PCB directly and imported the foot close to the module. In order to reduce the noise and interfere with. The collinear distance of cloth should be appropriate on PCB, the electric potential change that the interference causes while avoiding the switch.

In addition, consider heavy current may cause the interference to IPM lead wire of the external driving circuit, can be between the pin 1~4, 3~4, 4~5 add the filter capacitor according to interfering with the magnitude.

Protection circuit design of 4 IPM

Because the protective circuit that IPM offers does not possess the self-protection function. So should offer inside through the peripheral hardware or accessory circuit of the software: FO signal changed into the control signal of blockading IPM. Shut off IPM, realize and protect.

4. A hardware

When IPM is out of order, FO exports the low level, reaches the circuit of the hardware through the high-speed photosensitive resister, shut off PWM to export, thus achieve the goal of protecting IPM. The concrete hardware connection mode is as follows: 3 attitude transceivers with control end of PWM interface circuit head that here (such as 74HC245) . PWM signal sent to IPM interface circuit after 3 attitude transceivers. The trouble outcoming signal FO of IPM is outputted and sends the negate AND gate by light-coupled isolation. It can carry OE to make to send 3 more to attitude transceivers. IPM normal working hour. It is the low level with Africa’s gate output. 3 attitude transceivers are strobed; When IPM is out of order. It is the high level with Africa’s gate output. 3 attitude transceivers all outputs are put as the high impedance state. Blockade the control signal of each IPM. Shut off IPM. Realize and protect.

4. 2 software

When IPM is out of order. FO exports the low level, the high-speed photosensitive resister of FO signal passing is sent to the control device and dealt with. After the processor is confirmed. Utilize cutting off or software to shut off PWM control signal of IPM. Thus achieve the goal of protecting. Such as in the system that is controlled on the basis of DSP. Utilize supervisor middle-power of the incident to drive and protect the pin (PDPINT) Stop realizing the protection of IPM. 1 the intersection of incident and multi-channel PWM that supervisor born severely can control a plurality of IPM work usually. Among them each gas switching tube can output FO signal, FO signal passing AND-gate of each gas switching tube. Export the low level, and gate output low level when any gas switching tube is out of order. Connect this pin to PDPINT, because PDPINT, in order that DSP cuts off at the time of the low level, all piece supervisors export the pin and is set up as the high impedance state by the hardware, thus achieve the goal of protecting.

The above-mentioned 2 kinds of schemes utilize IPM trouble outcoming signal to blockade the control signal channel of IPM. Therefore has remedied IPM one’s own protective deficiency, the protective device effectively.

Buffer circuit design of 5 IPM

In IPM employs, because high-frequency switching process and loop parasitic inductance of the power,etc. will produce the greater impact to the device to superpose di/ dt, dv/ dt and instant power consumption produced, vulnerableness device. So need to set up the buffer circuit (namely absorbing circuit) ,The purpose is to change the switch orbit of the device, control various transient overvoltage, reduce the switching loss of the device. Safe operation of the protective device.

Fig. 4 is 3 kinds of commonly used IPM buffer circuit. Fig. 4(a) For not only having buffer circuit that a sense capacitor forms only, turn the effective and low cost into the voltage to wink, suitable for low-powered IPM. Fig. 4(b) It is the buffer circuit that RCD forms, are relatively suitable for high-power IPM. Buffering the diode D can be clamped in wink and change voltage, thus inhibit the parasitic oscillation that may be caused because of the parasitic inductance of bus wire. Its RC time constant should be designed to be periodic 1/ 3 of switch, namely r =T/ 3 =1/ 3f. Fig. 4© For P type RCD and buffer circuit that the N-type RCD forms, are suitable for high-power IPM. The function is similar to Fig. 4(b) The buffer circuit illustrated, the inductance of its loop is less. If cooperate with using Fig. 4(a) at the same time Buffer circuit illustrated. Still can reduce the stress of buffering the diode, it is better to buffer the result.

In Fig. 4© China, when IGBT shuts off. Load current buffer into diode to buffer condenser charge, the collector current is reduced gradually at the same time, because the voltage of the end of capacitor two can’t change suddenly. So has limited IGBT collecting electrode voltage build-up rate dv/ dt effectively. Also prevented collector voltage and collector current from maximizing at the same time. Energy that stray inductance stores when IGBT opens within IGBT collecting electrode bus wire inductor, circuit and component, store in the buffer capacitor at this moment. When IGBT opens, collecting electrode bus wire inductance and other stray inductance limit IGBT collector current climbing rate di/ dt effectively. Have prevented collector voltage and collector current from maximizing at the same time too. At this moment, the buffer capacitor discharges through connecting resistor and IGBT switch, its switch energy stored thereupon dissipates on the resistor in connecting resistor, circuit, component too. Like this, transfer the switching loss that IGBT runtime produces to the buffer circuit. Dissipate on the relevant resistor in the form of heat finally, thus protect IGBT safe operation.

Fig. 4© The resistance quantity and capacitance value of China are chosen according to the empirical data: If the capacitance value of PM200DSA060 is 0. 221xF~0. 47xF, the withstand voltage value is 1 of IGBT. From 1 time to 1. 5 times, is resistance quantity 10? -20? ,The resistance power presses P =FCU2xlO-6 calculates, among them f is IGBT operating frequency, u is the working peak voltage of IGBT. C is the buffer circuit and series capacity of the resistor. The diode chooses the fast recovery diode. In order to guarantee the reliability of the buffer circuit, can choose to capsulate the good buffer circuit illustrated in Fig. 4 according to the power magnitude.

In addition, because the stray inductance within bus wire inductor, buffer circuit and component has maximal influence on IPM, especially high-power IPM, it is good to be small. It needs the hand from many aspects to reduce the inductance: The direct-flow bus wire should be lacked trying hard; The buffer circuit should near the module as much as possible; Choose low inductive propene polymer electrodeless capacitor, fast buffer diode matched with IPM and have no sense to discharge the resistor.

6 IPM application in the single-phase full-bridge inverter

The inverter circuit of single-phase full-bridge illustrated in Fig. 5 is mainly made up of inverter circuit and controlling circuit. The inverter circuit includes reversing full-bridge and smoothing circuit, among them reverse the full-bridge and finish running to the variety that is exchanged continuously. The harmonic composition of filtration of smoothing circuit, in order to get required alternating current; The controlling circuit finishes the concurrent implementation of control on gas switching tube in the bridge inverter and protects the function partly.

The picture one is made up of 4 gas switching tubes and 4 fly-wheel diodes against turning into the full-bridge, make-and-break under the high-frequency condition of the gas switching tube while working. Switch snap switch tube-voltage and electric current become great, it is great to loss, junction temperature rises, in addition, loop parasitic inductance of power, shaking and noise,etc.. It is extremely apt to cause the gas switching tube to be damaged instant, design protective circuit and driving circuit of the gas switching tube with daily discrete component in the past, cause the circuit hugely and unreliable.

I adopt a pair of a pair of unit IPM module PM200DSA060s to replace in the picture separately Vl, D1, V2, D2 making up and V3, D3, v4, D4 make up and form inverter circuit of the full-bridge, utilize DSP control on IPM, finish the designs and debugging of the intermediate frequency 20kW, 230V inverter, have adopted driving circuit as stated above, Fig. 4© Buffer circuit and software IPM protective circuit based on that DSP controls of China. Design practice to show: Use IPM reducible system hardware circuit, shorten systematic development time, improve reliability, reduced volume, improve protective power.