Operation of a H4RG-10 in the NASA Goddard Astrophyiscs Divison IR Detector Lab Testbed

Future space and ground based missions in the near infrared are planning to or will utilize the next generation of Teledyne's HxRG detectors, the HgCdTe 4K x 4K array (H4RG). The science cases of such missions will require optimal stability and noise performance. To assess the detailed performance of the H4RG, we have developed a small single detector testbed in NASA Goddard's Astrophysics Division IR detector lab. The testbed operates a H4RG array inside a large dewar using a room temperature Leach controller. The dewar will include two integrating spheres with controlled apertures using NIR LEDs as light sources as well as a calibrated photodiode to precisely measure flux. We present preliminary results of a banded H4RG-10 array on the bench. In the near future, we plan to use the test bed to investigate the specific origins of electronic noise in the test bed, persistence, and other flux dependent nonlinearities

Next-Generation Microshutter Arrays for Large-Format Imaging and Spectroscopy

A next-generation microshutter array, LArge Microshutter Array (LAMA), was developed as a multi-object field selector. LAMA consists of small-scaled microshutter arrays that can be combined to form large-scale microshutter array mosaics. Microshutter actuation is accomplished via electrostatic attraction between the shutter and a counter electrode, and 2D addressing can be accomplished by applying an electrostatic potential between a row of shutters and a column, orthogonal to the row, of counter electrodes. Microelectromechanical system (MEMS) technology is used to fabricate the microshutter arrays. The main feature of the microshutter device is to use a set of standard surface micromachining processes for device fabrication. Electrostatic actuation is used to eliminate the need for macromechanical magnet actuating components. A simplified electrostatic actuation with no macro components (e.g. moving magnets) required for actuation and latching of the shutters will make the microshutter arrays robust and less prone to mechanical failure. Smaller-size individual arrays will help to increase the yield and thus reduce the cost and improve robustness of the fabrication process. Reducing the size of the individual shutter array to about one square inch and building the large-scale mosaics by tiling these smaller-size arrays would further help to reduce the cost of the device due to the higher yield of smaller devices. The LAMA development is based on prior experience acquired while developing microshutter arrays for the James Webb Space Telescope (JWST), but it will have different features. The LAMA modular design permits large-format mosaicking to cover a field of view at least 50 times larger than JWST MSA. The LAMA electrostatic, instead of magnetic, actuation enables operation cycles at least 100 times faster and a mass significantly smaller compared to JWST MSA. Also, standard surface micromachining technology will simplify the fabrication process, increasing yield and reducing cost

Development of a somatosensory controller for positioning a manipulator device for picking apples

The aim of the study is to develop a somatosensory controller for remote control of a manipulator for picking apples using resistive sensors, a gyroscope and an accelerometer. A computer simulation of the process of picking fruits from a tree crown was carried out in the Gazebo simulator using a somatosensory controller. An environment has been created, including a model of a manipulator for picking apple fruits and a fruit tree, and the properties of the environment have been set. To conduct a comparative experiment to evaluate the results of computer simulation of the process of picking apple fruits using a self-sensor controller and a manufactured sample of a manipulator, artificial models of trees with an identical crown and the location of fruits in the crown at a distance of no more than 1,5 meters from the zero point of the manipulator were used. According to the results of the research, it was found that the average time for picking one apple fruit by a manufactured manipulator in an automated mode is 12,9 seconds, the minimum time was 9,4 seconds, the maximum 15,9 seconds. Gazebo environment using a self-touch controller was 11,7 seconds. The minimum time was 8 seconds, the maximum 14,9 seconds. The development of digital intelligent systems, telematic services will ensure the widespread use of the proposed method for monitoring and managing the group work of robotic tools in the cultivation of fruit and berry crops

The reactivity of organosilicon derivatives of phosphorus in addition reactions

The results of studies of the reactivity of organosilicon derivatives of tricoordinate and tetracoordinate phosphorus containing the P–X–Si (X = O, N, or S) groups in reactions involving addition to various unsaturated systems are examined and surveyed. Attention has been concentrated on the elucidation of the specific influence of the trialkylsilyl group on the character of the reaction of phosphorus–silicon compounds. The bibliography includes 137 references. © 1984 The British Library

A luminous blue kilonova and an off-axis jet from a compact binary merger at z=0.1341

The recent discovery of a faint gamma-ray burst (GRB) coincident with the gravitational wave (GW) event GW 170817 revealed the existence of a population of low-luminosity short duration gamma-ray transients produced by neutron star mergers in the nearby Universe. These events could be routinely detected by existing gamma-ray monitors, yet previous observations failed to identify them without the aid of GW triggers. Here we show that GRB150101B was an analogue of GRB170817A located at a cosmological distance. GRB 150101B was a faint short duration GRB characterized by a bright optical counterpart and a long-lived X-ray afterglow. These properties are unusual for standard short GRBs and are instead consistent with an explosion viewed off-axis: the optical light is produced by a luminous kilonova component, while the observed X-rays trace the GRB afterglow viewed at an angle of ~13 degrees. Our findings suggest that these properties could be common among future electromagnetic counterparts of GW sources.Comment: 28 pages, 8 figures, 2 tables. Accepted for publicatio

Programmable Aperture with MEMS Microshutter Arrays

A microshutter array (MSA) has been developed for use as an aperture array for multi-object selections in James Webb Space Telescope (JWST) technology. Light shields, molybdenum nitride (MoN) coating on shutters, and aluminum/aluminum oxide coatings on interior walls are put on each shutter for light leak prevention, and to enhance optical contrast. Individual shutters are patterned with a torsion flexure that permits shutters to open 90 deg. with a minimized mechanical stress concentration. The shutters are actuated magnetically, latched, and addressed electrostatically. Also, micromechanical features are tailored onto individual shutters to prevent stiction. An individual shutter consists of a torsion hinge, a shutter blade, a front electrode that is coated on the shutter blade, a backside electrode that is coated on the interior walls, and a magnetic cobalt-iron coating. The magnetic coating is patterned into stripes on microshutters so that shutters can respond to an external magnetic field for the magnetic actuation. A set of column electrodes is placed on top of shutters, and a set of row electrodes on sidewalls is underneath the shutters so that they can be electrostatically latched open. A linear permanent magnet is aligned with the shutter rows and is positioned above a flipped upside-down array, and sweeps across the array in a direction parallel to shutter columns. As the magnet sweeps across the array, sequential rows of shutters are rotated from their natural horizontal orientation to a vertical open position, where they approach vertical electrodes on the sidewalls. When the electrodes are biased with a sufficient electrostatic force to overcome the mechanical restoring force of torsion bars, shutters remain latched to vertical electrodes in their open state. When the bias is removed, or is insufficient, the shutters return to their horizontal, closed positions. To release a shutter, both the electrode on the shutter and the one on the back wall where the shutter sits are grounded. The shutters with one or both ungrounded electrodes are held open. Sub-micron bumps underneath light shields and silicon ribs on back walls are the two features to prevent stiction. These features ensure that the microshutter array functions properly in mechanical motions. The MSA technology can be used primarily in multi-object imaging and spectroscopy, photomask generation, light switches, and in the stepper equipment used to make integrated circuits and MEMS (microelectromechanical systems) devices

Strawberry yield monitoring based on a convolutional neural network using high-resolution aerial orthoimages

This article presents the results of studies comparing the quality of work of two modern models of convolutional neural networks YOLOv7 and YOLOv8 used to monitor the yield of strawberries. To do this, we used the transfer method of machine learning models on a set of collected data consisting of four classes of development of generative formations of strawberry. As a result of the study, we obtained a data set that contained images of flowers, ovaries, mature and not mature berries. To ensure the balance of classes in the dataset, the Oversampling method was used, which included the generation of new images by applying various operations, such as resizing the image, normalizing brightness and contrast, converting images by rotating them by a certain angle and reflection, random noise addition, Gaussian blur. To collect data (images) in the field, a DJI Phantom 2 quadrocopter with a DJI Zenmuse Gimbal suspension and a GoPro HD HERO3 camera was used. To assess the quality of the YOLOv7 and YOLOv8 models when recognizing specified classes, well-known metrics were used that estimate the proportion of objects found that are really objects of a given class, such as Precision, Recall and mAP. Analysis of the results showed that the mAP metric for all classes of the YOLOv7 convolutional neural network model was 0,6, and the YOLOv8 model was 0,762. Analysis of the test sample images showed that the average absolute percentage error of image recognition of all classes by the YOLOv7 and YOLOv8 models was 9,2%. The most difficult to recognize was class the ovary of strawberries, the average absolute percentage error of which was 13,2%. In further studies, the use of high-resolution stereo cameras is recommended, which will further improve the accuracy of monitoring potential yields due to the possibility of determining the dimensional parameters of strawberry fruits and constructing 3D models of elevation maps using photogrammetry