3DCLIMBER: Climbing and manipulation over 3D structures

This paper describes the development of a novel pole climbing robot with the ability of climbing and manipulating across 3D structures, like petrochemical pipelines. The robot consists of a 4-DOF serial climbing mechanism and two grippers. Unlike many other developed pole climbing robots, 3DCLIMBER can overcome bends, T-junctions, flanges, and sharp changes on the pole’s diameter. With the current gripper, the robot can operate on circular profiles with diameters ranging from 200 mm to 350 mm and is able to scan the exterior surface of the pole. Existence of separate gripping and climbing modules allows application of various grippers for different profile shapes and sizes without any change on the climbing mechanism. In case of power failure the robot maintains its status without slipping on the structure. Furthermore, some nondestructive test operations require fine manipulation over the structure. Fine manipulation with an industrial arm encounters many well known difficulties. Such difficulties become even more problematic when the base of the robot’s arm is mobile. This problem was addressed by a robotic proprioception solution embedded into the robot by integration of inclinometers and range finder sensors as well as error compensation and self calibration algorithms. The proposed algorithms and sensors significantly improved the manipulation accuracy of the robot.     

Utilization of various starter cultures in the production of Amasi, a Zimbabwean naturally fermented raw milk product

Fermented milk was prepared from unpasteurised milk using natural fermentation (R), back-slopping (B) and by addition of two different starter cultures (C1 and DL). The numbers of Escherichia coli, coliforms, lactic acid bacteria (LAB) and the changes in pH, carbohydrates, organic acids and volatile compounds were recorded during 48-h fermentation. After 48-h fermentation, the highest numbers of E. coli were found in R and B fermentations and the lowest in the DL fermentation. The DL culture reduced the pH faster than the other starter cultures. The DL and C1 had higher levels of LAB in the beginning of the fermentation than the other two. Galactose and lactic acid increased fastest in the DL and C1 fermentation, and R was slowest. The highest levels of succinate, ethanol and malty compounds were found in the R and B fermentations. Lower levels of LAB in the first part of the fermentations, but higher number of E. coli could explain the increased levels of succinate, ethanol and malty compounds.     

Directional velocity estimation using a spatio-temporal encoding technique based on frequency division for synthetic transmit aperture ultrasound

This paper investigates the possibility of flow estimation using spatio-temporal encoding of the transmissions in synthetic transmit aperture imaging (STA). The spatial encoding is based on a frequency division approach. In STA, a major disadvantage is that only a single transmitter (denoting single transducer element or a virtual source) is used in every transmission. The transmitted acoustic energy will be low compared to a conventional focused transmission in which a large part of the aperture is used. By using several transmitters simultaneously, the total transmitted energy can be increased. However, to focus the data properly, the signals originating from the different transmitters must be separated. To do so, the pass band of the transducer is divided into a number of subbands with disjoint spectral support. At every transmission, each transmitter is assigned one of the subbands. In receive, the signals are separated using a simple filtering operation. To attain high axial resolution, broadband spectra must be synthesized for each of the transmitters. By multiplexing the different waveforms on different transmitters over a number of transmissions, this can be accomplished. To further increase the transmitted energy, the waveforms are designed as linear frequency modulated signals. Therefore, the full excitation amplitude can be used during most of the transmission. The method has been evaluated for blood velocity estimation for several different velocities and incident angles. The program Field II was used. A 128-element transducer with a center frequency of 7 MHz was simulated. The 64 transmitting elements were used as the transmitting aperture and 128 elements were used as the receiving aperture. Four virtual sources were created in every transmission. By beamforming lines in the flow direction, directional data were extracted and correlated. Hereby, the velocity of the blood was estimated. The pulse repetition frequency was 16 kHz. Three different setups were investigated with flow angles of 45, 60, and 75 degrees with respect to the acoustic axis. Four different velocities were simulated for each angle at 0.10, 0.25, 0.50, and 1.00 m/s. The mean relative bias with respect to the peak flow for the three angles was less than 2%, 2%, and 4%, respectively.     

Infrared and Raman spectroscopy study of alkyl hydroxamic acid and alkyl hydroxamate isomers

The isomeric structures of alkyl hydroxamic acid, as well as its potassium salt, sodium salt, and an alcohol complex, have been characterized in the solid, liquid, and gaseous states by Fourier transform infrared (FT-IR) and FT-Raman spectroscopy. Raman spectroscopy provides insight into the long-standing debate over the isomeric composition of hydroxamates in the solid state and in an aqueous basic solution. IR and Raman results are not consistent with the enol isomer existing in the solid or liquid states of octyl or decyl hydroxamic acid, potassium hydroxamate, and sodium hydroxamate. The infrared and Raman spectra of these compounds provide clear and convincing evidence regarding their chemical structure, mainly from amide-type carbonyl, NH bending, and OH/NH stretching bands. Vibrational spectroscopy is sensitive to polar (FT-IR) and non-polar (FT-Raman) vibrations and the influence of ionic and hydrogen bonding on these vibrations, and these abilities are particularly useful for characterizing keto versus enol and trans versus cis conformations in alkyl hydroxamic acid and its salts. Evolved gas analysis (EGA) in a nitrogen gas environment of alkyl hydroxamic acid and its salts is also discussed. EGA data reveal that water is not incorporated into the solid-state crystal structure of alkyl hydroxamic acid or the potassium salt; however, the sodium salt form is found to have a stable hydrate conformer that is shown to affect the Z isomer (NH trans to carbonyl, OH cis to carbonyl) IR absorbance bands. EGA data also indicates results that could be of interest to bio-pharmaceutical applications involving nitric oxide donation.     

High frame-rate blood vector velocity imaging using plane waves: simulations and preliminary experiments

Conventional ultrasound methods for acquiring color images of blood velocity are limited by a relatively low frame-rate and are restricted to give velocity estimates along the ultrasound beam direction only. To circumvent these limitations, the method presented in this paper uses 3 techniques: 1) The ultrasound is not focused during the transmissions of the ultrasound signals; 2) A 13-bit Barker code is transmitted simultaneously from each transducer element; and 3) The 2-D vector velocity of the blood is estimated using 2-D cross-correlation. A parameter study was performed using the Field II program, and performance of the method was investigated when a virtual blood vessel was scanned by a linear array transducer. An improved parameter set for the method was identified from the parameter study, and a flow rig measurement was performed using the same improved setup as in the simulations. Finally, the common carotid artery of a healthy male was scanned with a scan sequence that satisfies the limits set by the Food and Drug Administration. Vector velocity images were obtained with a frame-rate of 100 Hz where 40 speckle images are used for each vector velocity image. It was found that the blood flow approximately followed the vessel wall, and that maximum velocity was approximately 1 m/s, which is a normal value for a healthy person. To further evaluate the method, the test person was scanned with magnetic resonance (MR) angiography. The volume flow derived from the MR scanning was compared with that from the ultrasound scanning. A deviation of 9% between the 2 volume flow estimates was found.