External Filters Research Articles

The impact of climate on the winter strategies of insects

The impact of climate on the winter strategies of insects

Design of optical/IR blocking filters for the Lynx X-ray Microcalorimeter

The Lynx mission concept, under development ahead of the 2020 Astrophysics Decadal Review, includes the Lynx X-ray Microcalorimeter (LXM) as one of its primary instruments. The LXM uses a microcalorimeter array at the focus of a high-throughput soft x-ray telescope to enable high-resolution nondispersive spectroscopy in the soft x-ray waveband (0.2 to 15 keV) with exquisite angular resolution. Similar to other x-ray microcalorimeters, the LXM uses a set of blocking filters mounted within the dewar that pass the photons of interest (x-rays) while attenuating the out-of-band long-wavelength radiation. Such filters have been successfully used on previous orbital and suborbital instruments; however, the Lynx science objectives, which emphasize observations in the soft x-ray band (<1keV), pose more challenging requirements on the set of LXM blocking filters. We present an introduction to the design of the LXM optical/IR blocking filters and discuss recent advances in filter capability targeted at LXM. In addition, we briefly describe the external filters and the modulated x-ray sources to be used for onboard detector calibration.

Band Tunable Microcavity Perovskite Artificial Human Photoreceptors.

Electronic device versions of the neural functions of the human retina have high potential for use in artificial vision. This study demonstrates halide perovskite artificial human photoreceptors with specific photoresponses to red, green, and blue colors, which are consistent with human retinal photoreceiving cones and rods. In contrast to the current programmable spectral-response technologies, a novel microcavity structure is combined in this study with a perovskite absorber to achieve a targeted spectrum without using external optical filters. The fabricated artificial photoreceptors exhibit excellent performance including a high detectivity of more than 1013 Jones, a large linear dynamic range of 154 dB, and a short response time of 580 ns. These values are equal to or better than those of the natural human retina. These devices can easily be monolithically integrated on a single flexible substrate by using vacuum deposition, and a true proof-of-concept full-color image reconstruction is demonstrated.

The JET upgraded toroidal Alfvén Eigenmode Diagnostic System

The Alfvén Eigenmode Active Diagnostic system (AEAD) has undergone a major upgrade and redesign to provide a state-of-the-art excitation and real-time detection system for JET.The new system consists of individual 4 kW amplifiers allowing for increased current, separate excitation and real time control of relative phasing between antenna currents. The amplifiers have a frequency range of 10–1000 kHz, divided into various frequency bands by external matching filters. Due to the varying transmission line impedance throughout the frequency range, the amplifiers were designed with a very high resilience to reflected power.The existing amplifier control electronics have been replaced with a digital control system incorporating a National Instruments platform and Field Programmable Gate Array (FPGA) modules for frequency, gain and phase control with a frequency and phase resolution of less than 1 kHz and 1 degree respectively. Complementing the digital control system is the Protection and Control System, which utilizes Field Programmable Analog Arrays (FPAAs) and an array of electronic devices to monitor and control the AEAD.New capabilities such as independent antenna current/phase control, allow for improved excitation control, better definition of antenna spectrum combined with enhanced system reliability. This paper will review the new AEAD system, its unique capabilities and improvements over the previous diagnostic system.

Adaptive-Robust Control of a Class of EL Systems With Parametric Variations Using Artificially Delayed Input and Position Feedback

In this paper, the tracking control problem of an Euler-Lagrange system is addressed with regard to parametric uncertainties, and an adaptive-robust control strategy, christened Time-Delayed Adaptive Robust Control (TARC), is presented. TARC approximates the unknown dynamics through the time-delayed estimation, and the adaptive-robust control provides robustness against the approximation error. The novel adaptation law of TARC, in contrast to the conventional adaptive-robust control methodologies, requires neither complete model of the system nor any knowledge of predefined uncertainty bounds to compute the switching gain, and circumvents the over- and underestimation problems of the switching gain. Moreover, TARC only utilizes position feedback and approximates the velocity and acceleration terms from the past position data. The adopted state-derivatives estimation method in TARC avoids any explicit requirement of external low pass filters for the removal of measurement noise. A new stability notion in continuous-time domain is proposed considering the time delay, adaptive law, and state-derivatives estimation which in turn provides a selection criterion for gains and sampling interval of the controller.

Multichroic seashell antenna with internal filters by resonant slots and cold-electron bolometers

We have developed and realized a novel multichroic seashell antenna with internal bandpass filters by resonant slots and cold-electron bolometers (CEB). Slots and CEBs are connected by coplanar waveguides (CPW) instead of microstrip lines to realize the most reliable single-layer technology. The internal resonance is organized by a series resonance of slots with CPW and capacitances of superconductor/insulator/normal (SIN) tunnel junctions. In contrast, a conventional multichroic pixel consists of a wideband sinuous antenna coupled to TES detectors by long microstrip lines with overlap and external on-chip filters for different frequency bands. A common problem with a conventional multichroic pixel is that the beam width is frequency dependent for different frequency bands. Besides that, this system with external filters is quite large and includes long microstrip lines with unavoidable overlap and rater high losses. The multichroic seashell antenna with internal resonances avoids all these problems. The main advantage of this antenna is an opportunity to tune separate pairs of phased slots for each frequency band independently. We used pairs of λ/2 slots for 75 and 105 GHz, connected by CPW to CEBs. The connection of CPW to slots was shifted closer to the end of slots for proper RF matching. Each CEB included two SIN junctions and an absorber. SIN junctions had capacitances of 77 and 67 fF. Wave impedance of the antenna was near 50 Ohm and resistance of the absorber was matched to this value. RF testing was done at 314 mK irradiating this chip by frequency sweep of a generator from 78–118 GHz. The response curves have shown clear resonances around 75 and 105 GHz with a quality factor around 5. These experiments confirmed that the seashell antenna with the internal filters by resonant slots and CEBs could effectively be used for creating multiband elements.

SA49THE EFFECT OF CHILDHOOD TRAUMA ON BLOOD EXPRESSION OF MED22 IN PATIENTS WITH MAJOR DEPRESSIVE DISORDER IS MEDIATED BY CIS-ACTING SNPS

The quality of robotic laser welded parts is related to the joint location, the trajectory of the laser focal point and the process parameters. By performing in-process monitoring, it is possible to acquire sufficient process knowledge for post-inspection to evaluate the geometrical weld quality. The existing solutions for such systems operate along linear welds. This paper contributes with a quality inspection system for robot laser welding, that can handle double-curved geometries. The data acquisition system includes a CMOS camera, which is mounted such that it looks through the laser optics, external LED illumination and matching optical filters. During the process, the area around the moving laser focal point is captured, resulting in a sequence of images. The trajectory of the focal point is determined by estimating the 2D displacement field between each image using template matching and subsequently filtering the data through a Kalman filter to improve the accuracy and robustness of the system. The joint location is determined by applying a Canny edge detector and a standard Hough transform within a specified region of interest. As this paper deals with double-curved geometries, the region of interest is moved in relation to the laser trajectory, such that it always contains the visible part of the joint, that is closest to the focal point. The developed post-inspection system evaluates the quality of the weld by comparing the estimated trajectory relative to the determined location of the joint. The performance of the proposed quality inspection system was validated empirically on 18 samples. The tests showed promising results, as the system was able to accurately detect changes in the welding trajectory relative to the location of the joint with an accuracy of ± 0.2 mm.

Quality Inspection System for Robotic Laser Welding of Double-Curved Geometries

The quality of robotic laser welded parts is related to the joint location, the trajectory of the laser focal point and the process parameters. By performing in-process monitoring, it is possible to acquire sufficient process knowledge for post-inspection to evaluate the geometrical weld quality. The existing solutions for such systems operate along linear welds. This paper contributes with a quality inspection system for robot laser welding, that can handle double-curved geometries. The data acquisition system includes a CMOS camera, which is mounted such that it looks through the laser optics, external LED illumination and matching optical filters. During the process, the area around the moving laser focal point is captured, resulting in a sequence of images. The trajectory of the focal point is determined by estimating the 2D displacement field between each image using template matching and subsequently filtering the data through a Kalman filter to improve the accuracy and robustness of the system. The joint location is determined by applying a Canny edge detector and a standard Hough transform within a specified region of interest. As this paper deals with double-curved geometries, the region of interest is moved in relation to the laser trajectory, such that it always contains the visible part of the joint, that is closest to the focal point. The developed post-inspection system evaluates the quality of the weld by comparing the estimated trajectory relative to the determined location of the joint. The performance of the proposed quality inspection system was validated empirically on 18 samples. The tests showed promising results, as the system was able to accurately detect changes in the welding trajectory relative to the location of the joint with an accuracy of ± 0.2 mm.

Application of portable near-infrared spectrometer to Heliotron J plasma diagnostics.

A simple near-infrared (NIR) spectrometer with a wavelength range of 898-2130 nm has recently been applied to diagnose Heliotron J plasmas. It adopts a symmetrical crossed Czerny-Turner mount equipped with a thermoelectrically cooled 512 channel InGaAs linear sensor. Reciprocal linear dispersion was deduced to 96.37 nm/mm at the center of the detector. External filters can be inserted into the path of the collection optics to reject second-order spectra, as needed. Absolute intensity calibration was performed together with a visible spectrometer using a tungsten halogen lamp, and the effect of the transmittance fringe in the visible region of the applied long-pass filter on the NIR calibration was investigated. The intended application of the NIR spectrometer includes extending the wavelength region of a spectral monitor to less contaminated regions for Heliotron J plasma studies. In preliminary measurements, we observed the Paschen series for the hydrogen pellet injection plasma and two atomic helium lines, i.e., 2S-2P singlet and triplet lines, in helium gas puffing experiments. A continuum spectrum in this regime that is attributable to black-body radiation from hot spots on the plasma-facing components was identified. In addition, this may also be used to monitor background radiation in the YAG-Thomson scattering signals near 1064 nm.

Photonic band engineering in absorbing media for spectrally selective optoelectronic films.

Spectrally selective materials are of great interest for optoelectronic devices in which wavelength-selectivity of the photoactive material is necessary for applications such as multi-junction solar cells, narrow-band photodetectors, transparent photovoltaics, and tailored emission sources. Achieving controlled transparency or opacity within multiple wavelength bands in the absorption, reflection, and transmission spectra are difficult to achieve in traditional semiconductors that typically absorb at all energies above their electronic band gap and is generally realized by the use of external bandpass filters. Here, we propose an alternate method for achieving spectral selectivity in optoelectronic thin films: the use of photonic band engineering within the absorbing region of a semiconductor in which resonant photonic bands are strongly coupled to the external reflectivity and transmission spectra. As a first step, we use optical simulations to systematically study the effect of material absorption on the properties of the photonic bands in a photonic crystal slab structure. We find that adding a weak loss to the materials model does not appreciably change the frequencies of the photonic bands but does reduce the quality factor of the associated photonic modes. Critically, the radiating photonic bands induce strong Fano resonance features in the transmission and reflection spectra, even in the presence of material absorption, due to coupling between the bands and external electromagnetic plane waves. These resonances can be tuned by adjusting the photonic crystal structural properties to induce spectral selectivity in the absorbing region of semiconductors. Lastly, we demonstrate this tuning method experimentally by fabricating a proof-of-principle photonic structure consisting of a self-assembled polystyrene bead monolayer infiltrated with PbS CQDs that displays both near-infrared absorption enhancement and visible transparency enhancement over a homogeneous control film, qualitatively matching predictions and showing promise for optoelectronic applications.

Experimental management of Oreochromis niloticus fingerlings, feeding with commercial rations and pre/probiotic

he Tilapia (Oreochromis niloticus) in Brazilian aquaculture accounts for 45% of continental fish production, with 219.33 thousand tons of fish. National tilapia farming is conducted with intensive management, exposing the fish to adverse crop situations. The objective of the experiment was to study the performance of tilapia fingerlings, fed commercial and pre/probiotic rations. The experiment was carried out at the Laboratory of Aquatic Organisms - LOA, which was set up at the Promove Faculties of Brasília - ICESP, Águas Claras campus - DF. The fifty-five tilapia fingerlings originated from Modelo Ipê Farm were used. The experiment was carried out in 40-liter rectangular aquariums containing external filters and microporous stones attached to air compressors. During the whole experiment, water quality parameters were monitored daily: temperature, dissolved oxygen concentration OD2 (mg/L), pH and ammonia (mg/L). For the removal of organic matter from aquariums composed of faeces and feed remains, the aquariums were siphoned and the water renewed daily. The water quality parameters of the experiment, phases 1 and 2, were within the limits recommended for tilapia, except the ammonia that presented high concentrations for the species. The good practices of low storage density management, high water renewal, external filtration system, constant aeration and feed utilization with pre and probiotics kept the fingerlings alive, even in experimental conditions and of presumed bacterial presence Edwardsiella tarda.

Efficacy of laser-assisted deep sclerectomy surgery for open angle glaucoma

Objective To evaluate the efficacy of CO2 laser-assisted deep sclerectomy surgery for the treatment of open angle glaucoma. Methods The data of 76 eyes of 61 patients with open angle glaucoma from Jan.2016 to Mar.2017 were collected and analyzed retrospectively. All cases were randomly divided into observed group and control group. Observed group, 32 eyes of 27 cases, received CO2 laser-assisted deep sclerectomy surgery. In observed group, there were 23 eyes of 20 males and 9 eyes of 7 females. The average age was (47.22±11.15) years.The control group, 44 eyes of 34 cases, underwent traditional trabeculectomy. There were 32 eyes of 23 males and 12 eyes of 11 females, the average age was (47.60±14.51) years in control group. The efficacy between the two groups were compared. Results The follow-up period was 8-15 months, average (9.10±2.40) months. The preoperative IOP in observed group and control group was (36.78±6.36)mmHg and (37.50±5.30)mmHg (1mmHg=0.133 kPa), respectively. The difference was not significant between the two groups (P=0.609). Six months after surgery, IOP were (15.86±2.85)mmHg and (16.61±3.31)mmHg in observed group and control group, respectively. The difference was not statistically significant between the two groups (P=0.611). IOP after surgery were lower than that before surgery (P<0.05). In observed group, the functional bleb was diffused and swelling 1week after surgery. One month after surgery, the function bleb with the coexistent modality and internal filtering type accounted for 84.38%, the external filtering accounted for 12.50%. At the last follow-up, the modality of filtering bleb was converted from the external filtering to the coexisting form. The functional bleb 6 months after surgery in the observed group was smaller than that in the control group (P=0.040). The success rate was 87.96% and 79.54% in observed group and control group respectively (P=0.395). Early postoperatively, the shallow ciliary detachment occurred in 1 eye (3.13%) in observed group. Delayed formation of anterior chamber, hyphema and choroidal detachment occurred in 20 eyes (45.45%) in control group. The difference in complication was significant between the two groups (χ2 =16.600, P=0.000). Conclusion The surgery CO2 laser-assisted deep sclerectomy is an effective and safe treatment for open angle glaucoma, with fewer complications in early postoperatively, and the internal flow of aqueous humor is dominant. Key words: Glaucoma, open-angle; Sclerectomy, deep; CO2 laser-assisted

Multiple Metamaterial Pattern Integration for Polarization Selective Photodetector Applications

ABSTRACTInterest in active metamaterial (MM) devices has recently increased due to their potential for tunable, switchable, and scalable optical responses. More specifically, a dynamic, on-chip MM polarizer has applications ranging from material characterization to sensing without the need for cumbersome external filters. This work demonstrates efforts to optimize MM devices for dynamic polarization filtering by combining elements from split-ring resonators, wire-pairs, and fishnet patterns. The polarization grid has been designed to operate under an applied voltage with simulated on/off ratios of 75% and dynamic polarization selectivity of 70%. Samples have been fabricated using epitaxial GaAs on sapphire with various n-type doping concentrations to approximate electrical tuning.

Optimized gate driver for high-frequency buck converter

With the increasing system complexity in the automotive business sector the integration of efficient and low electromagnetic emission (EME) switch mode power supplies (SMPS) is crucial. The main methods to bring down EME and keep high efficiency are to introduce external filters on the input and output sides, to use spread spectrum techniques on the switching frequency and to control the switching activity of output driver in the desired range. This paper presents the concept of output driver implementation with adaptive driver strength control and dead time optimization for high frequency buck converters with external power MOSFETs. The proposed concept allows the following characteristics to be achieved: improved control of switching activity in a closely defined range, efficiency optimization by minimization the body diode forward conduction, reduction of the reverse recovery losses and zero voltage switching. All these can be realized despite the unknown MOSFET technological parameter distribution (propagation on/off delay, gate resistance of the package, Miller gate charge) and the external parameters (temperature, input voltage, load current). The proposed concept was implemented for a 1.2 V output voltage and a 1.8 MHz switching frequency buck converter.

Novel Inductive Wireless Power Transfer Uplink Utilizing Rectifier Third-Order Nonlinearity

This paper proposes a new approach for inductive wireless power transfer (IWPT) tag-to-reader communication. A new technique to achieve transmitter/receiver (Tx/Rx) frequency separation is demonstrated. A two-tone Tx is adopted at the reader, and the third-order intermodulation (IM3) frequency generated by the tag rectifier nonlinearity is used as the Rx carrier, which is modulated by a baseband signal sent by the tag. The uplink signal at the IM3 frequency can be picked up by the reader coil. The IWPT impedance matching networks for both the reader and the tag coil can be reused efficiently, since the IM3 frequency at 5.06 GHz is close to the Tx fundamental frequencies at 4.94 and 5 GHz. Due to the Tx/Rx frequency separation, the Tx-to-Rx leakage at the Rx frequency can be suppressed by external filters to improve the Rx signal-to-noise ratio (SNR). The proposed technique is implemented within a 5-GHz IWPT system, and a tiny CMOS tag with a coil size of only 0.01 mm2 is used. This paper also implements conventional direct and intermediate frequency-based backscattering uplinks for comparison, and the proposed IM3 uplink is able to improve the Rx SNR by more than 20 dB. The achieved uplink data rate (100 kb/s) is also higher than the published work (20 kb/s) that adopted the conventional backscattering method.

Multi‐scale and antagonist selection on life‐history traits in parasitoids: A community ecology perspective

Abstract Life‐history traits within ecological communities can be influenced by regional environmental conditions (external filters) and community‐wide density‐dependent processes (internal filters). While traits in a regional context may converge to a narrow range of values because of environmental filtering, species belonging to a guild may present contrasting traits as a means of niche differentiation, allowing coexistence whilst exploiting the same resources. To disentangle the role of external and internal filters on phenotypic diversity within ecological communities, we examined the patterns of life‐history trait variation within a guild of insect parasitoids during two successive years across three contrasted regions in relation to several ecological factors. By combining a mean‐field approach and an analysis of phenotypic variance across organizational levels (from individual to guild), we showed that the patterns of life‐history trait variation across regions are consistent with local adaptation or adaptive phenotypic plasticity while the patterns of phenotypic variation within regions suggested how coexistence modulates life‐history traits expression through niche differentiation. Within a given region, phenotypic pattern of parasitoid life‐history traits may also arise from bottom‐up effects of trophic webs: insect host species could also control parasitoid life‐history traits in nature. Our results also showed that parasitoid life‐history traits presented contrasting variation patterns according to the sampling year, suggesting temporal variations in evolutionary and ecological dynamics of parasitoid species. The application of such trait‐based studies to insect parasitoids has the potential to provide further insight on how agricultural environments contribute to differential diversification among natural enemies guilds, highlighting the main role of agricultural landscape management for organisms'responses. A plain language summary is available for this article.

Fully Integrated Fluorescence Biosensors On-Chip Employing Multi-Functional Nanoplasmonic Optical Structures in CMOS

Integrated optical system-on-chip in silicon operating in the visible range can have a tremendous impact on enabling new applications in sensing and imaging through the ultra-miniaturization of complex optical instrumentation. CMOS technology has allowed an integration of optical detection circuitry for image sensors with massively large number of pixels. In this paper, we focus on techniques to realize complex optical-field processing elements inside CMOS by exploiting optical interaction with sub-wavelength metal nanostructures realized in the electrical interconnects layers, whose feature sizes are now in the sub-100-nm range. In particular, we present a fully integrated fluorescence-based bio-molecular sensor in 65-nm CMOS with integrated nanoplasmonic waveguide-based filters capable of more than 50 dB of rejection ratio across a wide range of incident angles. Co-designed with the integrated photo-detection circuitry, capacitive TIAs, and correlated double-sampling circuitry, the sensor is capable of detecting 48 zeptomoles of quantum dots on the surface with 52 fA of photodetector current with a fluorescence/excitation ratio of nearly −62 dB without any post-fabrication, external optical filters, lenses, or collimators. The ability to integrate complex nanoplasmonic metal structures with unique optical properties in CMOS with no post-processing creates the opportunity to enable large multiplexed assays on a single chip and a wide variety of applications, from in vitro to in vivo .

The Limits of Machine Ethics

Machine Ethics has established itself as a new discipline that studies how to endow autonomous devices with ethical behavior. This paper provides a general framework for classifying the different approaches that are currently being explored in the field of machine ethics and introduces considerations that are missing from the current debate. In particular, law-based codes implemented as external filters for action—which we have named filtered decision making—are proposed as the basis for future developments. The emergence of values as guides for action is discussed, and personal language –together with subjectivity- are indicated as necessary conditions for this development. Last, utilitarian approaches are studied and the importance of objective expression as a requisite for their implementation is stressed. Only values expressed by the programmer in a public language—that is, separate of subjective considerations—can be evolved in a learning machine, therefore establishing the limits of present-day machine ethics.

System Design of a 2.75-mW Discrete-Time Superheterodyne Receiver for Bluetooth Low Energy

This paper introduces a system-level approach to develop the first-ever fully discrete-time (DT) superheterodyne receiver (RX) for Internet-of-Things applications, such as Bluetooth low energy (BLE). It exploits fast switching speed and low internal capacitances of deep-nanoscale CMOS devices to realize a high intermediate-frequency (IF) architecture based on switched-capacitor-based charge-domain bandpass filtering. Power consumption is minimized by aggressively reducing the size of MOS devices and judiciously applying a sampling-rate decimation. The resultant increase in the flicker noise is mitigated by placing the IF frequency beyond the flicker corner frequency. Likewise, the decimation-induced aliasing is mitigated by DT filtering of preceding stages. The BLE RX is fully standard-compliant and achieves a record-low-power consumption of 2.75 mW (including its local oscillator) while delivering the state-of-the-art performance: 6.5-dB noise figure and −19-dBm third-order input intercept point, with a direct antenna connection and thus without the typical external bandpass filters.

A Bluetooth Low-Energy Transceiver With 3.7-mW All-Digital Transmitter, 2.75-mW High-IF Discrete-Time Receiver, and TX/RX Switchable On-Chip Matching Network

We present an ultra-low-power Bluetooth low-energy (BLE) transceiver (TRX) for the Internet of Things (IoT) optimized for digital 28-nm CMOS. A transmitter (TX) employs an all-digital phase-locked loop (ADPLL) with a switched current-source digitally controlled oscillator (DCO) featuring low frequency pushing, and class-E/F2 digital power amplifier (PA), featuring high efficiency. Low 1/ $f$ DCO noise allows the ADPLL to shut down after acquiring lock. The receiver operates in discrete time at high sampling rate (~10 Gsamples/s) with intermediate frequency placed beyond 1/ $f$ noise corner of MOS devices. New multistage multirate charge-sharing bandpass filters are adapted to achieve high out-of-band linearity, low noise, and low power consumption. An integrated on-chip matching network serves to both PA and low-noise transconductance amplifier, thus allowing a 1-pin direct antenna connection with no external band-selection filters. The TRX consumes 2.75 mW on the RX side and 3.7 mW on the TX side when delivering 0 dBm in BLE.