SIMBA: Tendon-Driven Modular Continuum Arm with Soft Reconfigurable Gripper

Crack evolution mechanism of stratified rock mass under different strength ratios and soft layer thickness: Insights from DEM modeling

We present here results obtained from three BeppoSAX observations of the accretion-powered X-ray pulsar SMC X-1 carried out during the declining phases of its 40--60 days long super-orbital period. Timing analysis of the data clearly shows a continuing spin-up of the neutron star. Energy-resolved timing analysis shows that the pulse-profile of SMC X-1 is single peaked at energies less than 1.0 keV whereas an additional peak, the amplitude of which increases with energy within the MECS range, is present at higher energies. Broad-band pulse-phase-averaged spectroscopy of the BeppoSAX data, which is done for the first time since its discovery, shows that the energy spectrum in the 0.1--80 keV energy band has three components, a soft excess that can be modeled as a thermal black-body, a hard power-law component with a high-energy exponential cutoff and a narrow and weak iron emission line at 6.4 keV. Pulse-phase resolved spectroscopy indicates a pulsating nature of the soft spectral component, as seen in a few other binary X-ray pulsars, with a certain phase offset with respect to the hard power-law component. Dissimilar shape and phase of the soft and hard X-ray pulse profiles suggest a different origin of the soft and hard components.

We present results from ASCA observations of the binary CI Cam both in quiescence and in outburst in order to identify its central accreting object. The quiescence spectrum of CI Cam consists of soft and hard components, which are separated clearly at around 2-3 keV. A large equivalent width of an iron K? emission line prefers an optically thin thermal plasma emission model to a nonthermal power-law model for the hard component, which favors a white dwarf as the accreting object, since optically thin thermal hard X-ray emission is a common characteristic among cataclysmic variables (binaries including an accreting white dwarf). However, since the power-law model, which represents the X-ray spectrum of the soft X-ray transients in quiescence, provides an equally good fit to the hard component statistically, we cannot exclude the possibility of a neutron star or a black hole from the quiescence data. The outburst spectrum, on the other hand, is composed of a hard component represented by multitemperature optically thin thermal plasma emission and an independent soft X-ray component that appears below 1 keV intermittently on a decaying light curve of the hard component. The spectrum of the soft component is represented well by a blackbody with the temperature of 0.07-0.12 keV overlaid with several K edges associated with highly ionized oxygen. This, together with the luminosity as high as ~1 ? 1038 ergs s-1, is similar to a supersoft source. The outburst in the hard X-ray band followed by the appearance of the soft blackbody component reminds us of recent observations of novae in outburst. We thus assume that the outburst of CI Cam is that of a nova and obtain the distance to CI Cam of 5-17 kpc by means of the relation between the optical decay time and the absolute magnitude. This agrees well with a recent estimate of the distance of 5-9 kpc in the optical band. All of these results from the outburst data prefer a white dwarf for the central object of CI Cam.

It is generally recognized that the cosmic radiation in the atmosphere consists of two components, the hard component and the soft. The interpretation of the soft component as the product of primary electrons which multiply in passing through the atmosphere according to the well‐known quantum mechanical principles is completely satisfactory but the hard component presents some serious difficulties. Its particles, the mesotrons, are undoubtedly produced as secondaries within the atmosphere, but what kind of primary particles produce the mesotrons has been until now an unsolved problem. If those particles were the electrons of the soft component, the soft component like the hard component would have to possess the distinguishing characteristic of its positive primaries of being asymmetrically distributed in angle in the regions near the equator. On the other hand, if the two components are independent, the soft component might show no asymmetry despite the fact that the hard component is known to be so strongly asymmetric that it must have been produced entirely by positive primaries.

The balance of inverted pendulum on inclined surfaces is the precursor to their control in unstructured environments. Researchers have devised control algorithms with feedback from contact (encoders - placed at the pendulum joint) and non-contact (gyroscopes, tilt) sensors. We present feedback control of Inverted Pendulum Cart (IPC) on variable inclines using non-contact sensors and a modified error function. The system is in the state of equilibrium when it is not accelerating and not falling over (rotational equilibrium). This is achieved when the pendulum is aligned along the gravity vector. The control feedback is obtained from non-contact sensors comprising of a pair of accelerometers placed on the inverted pendulum and one on the cart. The proposed modified error function is composed of the dynamic (non-gravity) acceleration of the pendulum and the velocity of the cart. We prove that the system is in equilibrium when the modified error is zero. We present algorithm to calculate the dynamic acceleration and angle of the pendulum, and incline angle using accelerometer readings. Here, the cart velocity and acceleration are assumed to be proportional to the motor angular velocity and acceleration. Thereafter, we perform simulation using noisy sensors to illustrate the balance of IPC on surfaces with unknown inclination angles using PID feedback controller with saturated motor torque, including valley profile that resembles a downhill, flat and uphill combination. The successful control of the system using the proposed modified error function and accelerometer feedback argues for future design of controllers for unstructured and unknown environments using all-accelerometer feedback.

We present measurements of the 0.05-10 MeV gamma-ray spectra as a function of longitude from the inner Galactic ridge using the Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory. The differential continuum emission relative to intensities at ±10° Galactic latitude appears to be a composite of at least three independent components: a soft low-energy component with a broad longitude distribution and with spectra well approximated by an exponentially absorbed power law; a hard component with a similarly broad longitude distribution modeled by a power law from ~200 keV to 10 MeV with photon index ~-1.75; and strong positron annihilation line and continuum contributions observed toward the center with intensities that decrease rapidly with longitude distance from the center. Although OSSE cannot distinguish between a simple one-component latitude distribution and a more complicated one with, for example, broad and narrow latitude components, an effective 5°-6° FWHM Gaussian latitude width gives a spectrum and intensity for the power-law component that agrees with extrapolations of measurements at higher energies using a cosmic-ray interaction model. However, the latitude distribution of the emission is not well measured. Near the Galactic center, bright variable sources contribute significantly to the low-energy spectrum. When account is taken of these variable-source contributions, both the soft low-energy and hard power-law components show a consistent longitude distribution that follows the Galactic matter distribution as evidenced by the Galactic CO distribution. These results, in conjunction with previous measurements, provide new information for determining the Galactic cosmic-ray electron spectrum at lower energies.

On the correlation between roping, texture, and morphology of aluminium alloy sheets

Evaluation of the angular distribution function of particles scattered in an amorphous medium is improved by deforming the integration path in the Fourier integral representation into the complex plane. That allows us to present the distribution function as a sum of two positive components, soft and hard, the soft component being close to a Gaussian, and the hard component vanishing in the forward direction, while including the Rutherford asymptotics and all the power corrections to it at large scattering angles. Detailed properties of those components, and their interplay at intermediate deflection angles are discussed. Comparison with the Moli\`{e}re theory is given.

AN ULTRASOFT EINSTEIN X-RAY SURVEY

This paper describes the modular magnetic assembly of reconfigurable, pneumatically actuated robots composed of soft and hard components and materials. The soft components of these hybrid robots are actuators fabricated from silicone elastomers using soft lithography, and the hard components are acrylonitrile–butadiene–styrene (ABS) structures made using 3D printing. Neodymium–iron–boron (NdFeB) ring magnets are embedded in these components to make and maintain the connections between components. The reversibility of these magnetic connections allows the rapid reconfiguration of these robots using components made of different materials (soft and hard) that also have different sizes, structures, and functions; in addition, it accelerates the testing of new designs, the exploration of new capabilities, and the repair or replacement of damaged parts. This method of assembling soft actuators to build soft machines addresses some limitations associated with using soft lithography for the direct molding of complex 3D pneumatic networks. Combining the self‐aligning property of magnets with pneumatic control makes it possible for a teleoperator to modify the structures and capabilities of these robots readily in response to the requirements of different tasks.

To investigate the physics of mass accretion onto weakly-magnetized neutron stars, 95 archival RXTE datasets of an atoll source 4U 1608-522, acquired over 1996-2004 in so-called upper-banana state, were analyzed. The object meantime exhibited 3-30 keV luminosity in the range of <~ 10^35 - 4 x 10^37 erg s^-1, assuming a distance of 3.6 kpc. The 3-30 keV PCA spectra, produced one from each dataset, were represented successfully with a combination of a soft and a hard component, of which the presence was revealed in a model-independent manner by studying spectral variations among the observations. The soft component is expressed by so-called multi-color disk model with a temperature of ~1.8 keV, and is attributed to the emission from an optically-thick standard accretion disk. The hard component is a blackbody emission with a temperature of ~2.7 keV, thought to be emitted from the neutron-star surface. As the total luminosity increases, a continuous decrease was observed in the ratio of the blackbody luminosity to that of the disk component. This property suggests that the matter flowing through the accretion disk gradually becomes difficult to reach the neutron-star surface, presumably forming outflows driven by the increased radiation pressure. On time scales of hours to days, the overall source variability was found to be controlled by two independent variables; the mass accretion rate, and the innermost disk radius which changes both physically and artificially.

&lt;p&gt;Film and television (TV) have been a way to view unthinkable worlds for many years. Physical props are a fundamental part of many films as they help to portray the story in the real world, which results in a more believable experience for the audience. The technology used in the production of props and creatures has evolved with the changes in the manufacturing process to allow for more computer-controlled designs. This begs the question; what could multi-property, 3D/4D printing bring to the way the film prop manufacturing industry creates physical props? Printing in the fourth dimension (dynamic) is a relatively new concept and is being researched by leading 3D printing companies. This area of study has yet to apply the four-dimensional (4D) capabilities of multi-property printing to the creation of heterogeneous humanoid anatomic’s. Heterogeneous 3D printing is the combination of multiple elements and material qualities in one print, which is possible by using the Stratasys J750 Polyjet printer. This printer allows for both hard and soft components to be incorporated into one design by blending the full-colour hard Vero material with soft, translucent Agilus material. The final humanoid objects have varying material hardness throughout the design, representing the different densities and materiality that is found in the finger joint. By taking the basic parameters of a section of human anatomy, the ability to create a creature by merely changing the size, colour, or the number of joints is achievable. With this technology, the ability to rapidly produce and easily edited final on-screen props is possible.&lt;/p&gt;

With the aim of reproducing the grasping and manipulation capabilities of humans, many robotic devices have been developed all over the world in more than 50 years of research, starting from very simple grippers, normally used in industrial activities, to very complex anthropomorphic robotic hands. Unfortunately, the reduced functionality and/or reliability of the devices developed so far prevent, together with the cost, their usability in unstructured environments, and in particular in human everyday activities. The adoption of design solutions inherited from conventional mechanics and the lack of purposely developed sensors and actuators are among the main causes of the partial fail in achieving the final goal of reproducing human manipulation capabilities. Our research activity aims at developing innovative solutions concerning the mechanical design, the sensory equipment and the actuation system for the implementation of anthropomorphic robotic hands with improved reliability, functionality and reduced complexity and cost, considering also aspects related to safety during human–robot interaction, paving the way toward the next generation of robotic hands.KeywordsAngular DisplacementTriangular ElementInnovative TechnologyTactile SensorFuse Deposition ModelingThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

This paper presents our solution for enabling a quadrotor helicopter, equipped with a laser rangefinder sensor, to autonomously explore and map unstructured and unknown indoor environments. While these capabilities are already commodities on ground vehicles, air vehicles seeking the same performance face unique challenges. In this paper, we describe the difficulties in achieving fully autonomous helicopter flight, highlighting the differences between ground and helicopter robots that make it difficult to use algorithms that have been developed for ground robots. We then provide an overview of our solution to the key problems, including a multilevel sensing and control hierarchy, a high-speed laser scan-matching algorithm, an EKF for data fusion, a high-level SLAM implementation, and an exploration planner.1 Finally, we show experimental results demonstrating the helicopter's ability to navigate accurately and autonomously in unknown environments.

It is now generally agreed that the cosmic radiation consists of two groups called the soft and the hard component. This classification refers to the penetrating power of the particles in question. The soft component consists of ordinary electrons and light quanta, whereas it now seems very probable that the hard group consists of "heavy electrons". The phenomena connected with the soft component are described by the cascade theory of showers put forward by Bhabha and Heitler (1937) and Carlson and Oppenheimer (1937). It is the purpose of the present paper to work out the consequences of the theory in greater detail in order to make possible a more quantitative comparison between theory and experiment than has hitherto been possible. This is desirable for several reasons: In the first place it is important to ascertain whether the phenomena connected with the soft component can be accountant for completely by the cascade theory or whether some of the facts require an explanation outside the present relativistic quantum mechanics.