A simple 5-DOF walking robot for space station application

Robots on the NASA space station have a potential range of applications from assisting astronauts during EVA (extravehicular activity), to replacing astronauts in the performance of simple, dangerous, and tedious tasks; and to performing routine tasks such as inspections of structures and utilities. To provide a vehicle for demonstrating the pertinent technologies, a simple robot is being developed for locomotion and basic manipulation on the proposed space station. In addition to the robot, an experimental testbed was developed, including a 1/3 scale (1.67 meter modules) truss and a gravity compensation system to simulate a zero-gravity environment. The robot comprises two flexible links connected by a rotary joint, with a 2 degree of freedom wrist joints and grippers at each end. The grippers screw into threaded holes in the nodes of the space station truss, and enable it to walk by alternately shifting the base of support from one foot (gripper) to the other. Present efforts are focused on mechanical design, application of sensors, and development of control algorithms for lightweight, flexible structures. Long-range research will emphasize development of human interfaces to permit a range of control modes from teleoperated to semiautonomous, and coordination of robot/astronaut and multiple-robot teams

A Silver/Silver Sulfide Selective Micro-Electrode Prepared by Chemical Treatment of Silver Wi

The preparation conditions and the performance of a small size Ag/Ag2S selective electrode are described. The analytical behaviour of this electrode, made by chemical treatment of a silver wire, is described in terms of potential - concentration curves, standard potential, lifetime and electrode selectivity. A series of electrodes have been prepared and investigated. Their response and selectivity to Ag+ and S2- are measured and compared with those of a commercial Orion silverlsulfide electrode. Several titrations were performed to evaluate the performances of the electrode. The investigated electrode can be used, as a good substitute for the commercial silverlsulfide electrode, in a wide variety of practical analytical systems

A hedonic analysis of factors impacting the value of planters on the used machinery market

A hedonic model was employed to examine factors that influence the resale price of row crop planters on the used machinery market. Planter sale data from 2016 to 2018 were utilized to conduct the analysis. Results suggested that the primary factors impacting planter resale prices were make, age, condition, planter configuration, row number, and row spacing. As a function of age (depreciation), planter values were generally determined to decrease at a decreasing rate. Finally, it was determined that there was a significant interaction between the variables make and age, suggesting that different planter makes depreciate differently

A polarographic method for following the rates of cholinesterase-catalyzed hydrolyses of acetylthiocholine

A rapid and simple polarographic method for following the rates of the cholinesterase-catalyzed hydrolysis of acetylthiocholine and the rates of inhibition of this hydrolysis is described. This method has the advantage that it can follow quite rapid reactions, as meaningful data can be obtained after 10 sec of mixing of the solutions. The method follows the rate of increase of the anodic polarographic wave of thiocholine produced by the hydrolysis. The validity of the method was determined by comparing the rates of production of thiocholine spectrophotometrically and polarographically. Also the values of Km for the hydrolysis, and Km and K1 for the inhibition reaction of neostigmine were determined and compared to values reported in the literature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31994/1/0000036.pd

The anodic dissolution of thin films of copper metal from pyrolytic graphite : A study of the multiple dissolution current peaks

The anodic stripping curves of electrodeposited thin films of copper have been investigated. Three distinct current peaks were observed. The more negative peak corresponded to copper macrolayers (copper on copper); the smaller peaks, found at more positive potentials were interpreted as mono-layer peaks which indicates that the copper interaction with pyrolytic graphite is greater than that of the copper-copper interaction. A method for preparing the monolayer films is described. Electronmicroprobe studies of the copper monolayer films indicated that the copper is uniformly distributed on the surface. These studies also showed that the macro layers started to grow at specific surface sites.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33374/1/0000772.pd

The relative noise levels of parallel axis gear sets with various contact ratios and gear tooth forms

The real noise reduction benefits which may be obtained through the use of one gear tooth form as compared to another is an important design parameter for any geared system, especially for helicopters in which both weight and reliability are very important factors. This paper describes the design and testing of nine sets of gears which are as identical as possible except for their basic tooth geometry. Noise measurements were made at various combinations of load and speed for each gear set so that direct comparisons could be made. The resultant data was analyzed so that valid conclusions could be drawn and interpreted for design use

Verifying, Challenging, and Discovering New Synapses Among Fully EM-Reconstructed Neurons in the Leech Ganglion

Neural circuits underpin the production of animal behavior, largely based upon the precise pattern of synaptic connectivity among the neurons involved. For large numbers of neurons, determining such “connectomes” by direct physiological means is difficult, as physiological accessibility is ultimately required to verify and characterize the function of synapses. We collected a volume of images spanning an entire ganglion of the juvenile leech nervous system via serial blockface electron microscopy (SBEM). We validated this approach by reconstructing a well-characterized circuit of motor neurons involved in the swimming behavior of the leech by locating the synapses among them. We confirm that there are multiple synaptic contacts between connected pairs of neurons in the leech, and that these synapses are widely distributed across the region of neuropil in which the neurons’ arbors overlap. We verified the anatomical existence of connections that had been described physiologically among longitudinal muscle motor neurons. We also found that some physiological connections were not present anatomically. We then drew upon the SBEM dataset to design additional physiological experiments. We reconstructed an uncharacterized neuron and one of its presynaptic partners identified from the SBEM dataset. We subsequently interrogated this cell pair via intracellular electrophysiology in an adult ganglion and found that the anatomically-discovered synapse was also functional physiologically. Our findings demonstrate the value of combining a connectomics approach with electrophysiology in the leech nervous system

Anatomy and activity patterns in a multifunctional motor neuron and its surrounding circuits

Dorsal Excitor motor neuron DE-3 in the medicinal leech plays three very different dynamical roles in three different behaviors. Without rewiring its anatomical connectivity, how can a motor neuron dynamically switch roles to play appropriate roles in various behaviors? We previously used voltage-sensitive dye imaging to record from DE-3 and most other neurons in the leech segmental ganglion during (fictive) swimming, crawling, and local-bend escape (Tomina and Wagenaar, 2017). Here, we repeated that experiment, then re-imaged the same ganglion using serial blockface electron microscopy and traced all of DE-3’s processes. Further, we traced back the processes of all of DE-3’s presynaptic partners to their respective somata. This allowed us to analyze the relationship between circuit anatomy and the activity patterns it sustains. We found that input synapses important for all of the behaviors were widely distributed over DE-3’s branches, yet that functional clusters were different during (fictive) swimming vs. crawling

Recent Decisions

Recent Decisions ADMIRALTY--COGSA--BILL OF LADING CARGO DESCRIPTION AND PACKER IDENTITY DETERMINE WHEN A CONTAINER IS A PACKAGE IN COGSA LIABILITY PROCEEDINGS Alan L. Marchisotto ============================ ADMIRALTY--JURISDICTION OVER AVIATION TORT CLAIMS--ADMIRALTY JURISDICTION DOES NOT EXTEND TO AVIATION TORT CLAIMS IN THE ABSENCE OF A SIGNIFICANT RELATIONSHIP BETWEEN THE TORT AND TRADITIONAL MARITIME ACTIVITIES W. H. Schwarzschild III ============================ ALIENS--ALIENS MAY MAINTAIN A CAUSE OF ACTION FOR PRIVATE EMPLOYMENT DISCRIMINATION UNDER 42 U.S.C. § 1981 (1970) Mark M. Greisberger ============================ ANTITRUST--ARTICLE 86 OF THE EEC TREATY APPLIES TO CERTAIN CHANGES IN INTERNAL CORPORATE STRUCTURE Richard P. Granfield =========================== CONSTITUTIONAL LAW--EXECUTIVE POWER--PRESIDENTIAL AUTHORITY TO NEGOTIATE FOREIGN COMMERCIAL AGREEMENTS PURSUANT TO FOREIGN AFFAIRS POWER IS NOT CIRCUMSCRIBED ABSENT EX-PLICIT LEGISLATION Donald B. Cameron, Jr. ========================== JURISDICTION--SECURITIES EXCHANGE ACT OF 1934--SECTION 10(b) APPLIES TO A TRANSACTION IN UNLISTED FOREIGN SECURITIES WHEN SIGNIFICANT FRAUDULENT CONDUCT OCCURS IN THE UNITED STATES Isaac H. Braddock ========================= TARIFFS--TRADE AGREEMENT CONCESSIONS MAY BE SUSPENDED ON A MOST-FAVORED-NATION BASIS WHEN SUCH TREATMENT IS REQUIRED BY INTERNATIONAL AGREEMENTS OF THE UNITED STATES David A. Boillo

Influence of Gear Design Parameters on Gearbox Radiated Noise

Spur and helical gears were tested in the NASA gear-noise rig to compare the noise produced by different gear designs. Sound power measurements were performed under controlled conditions for a matrix of operating conditions. Sound power was computed from near-field acoustic intensity scans taken just above the top surface of the gearbox. Test gears included four spur and five helical gear designs. The gears were designed to be as nearly identical as possible except for deliberate differences in tooth geometry and contact ratio. Test results are presented as a function of the gear design and operating conditions in the form of sound power charts and as narrow-band spectra