Monoclinic form I of clopidogrel hydrogen sulfate from powder diffraction data

The asymmetric unit of the title compound, C16H17ClNO2S+·HSO4 −, (I) [systematic name: (+)-(S)-5-[(2-chloro­phen­yl)(meth­oxy­carbon­yl)meth­yl]-4,5,6,7-tetra­hydro­thieno[3,2-c]pyridin-5-ium hydrogen sulfate], contains two independent cations of clopidogrel and two independent hydrogensulfate anions. The two independent cations are of similar conformation; however, this differs from that observed in ortho­rhom­bic form (II) [Bousquet et al. (2003 ▶). US Patent No. 6 504 030]. The H—N—Cchiral—H fragment shows a trans conformation in both independent cations in (I) and a gauche conformation in (II). In (I), classical inter­molecular N—H⋯O and O—H⋯O hydrogen bonds link two independent cations and two independent anions into an isolated cluster, in which two cations inter­act with one anion only via N—H⋯O hydrogen bonds. Weak inter­molecular C—H⋯O hydrogen bonds further consolidate the crystal packing

Studying the Excitation of Resonance Oscillations in a Rotor on Isotropic Supports by a Pendulum, a Ball, a Roller

We have analytically examined the steady motion modes of the system, composed of a balanced rotor on the isotropic elastic-viscous supports, and a load (a ball, a roller, a pendulum), mounted inside the rotor, thus enabling its relative motion. In this case, the pendulum is freely mounted onto the rotor shaft, while the ball or roller rolling without slipping along a ring track centered on the longitudinal axis of the rotor.The physical-mathematical model of the system has been described. We have recorded differential equations of the system's motion with respect to a coordinate system rotating at a constant speed of rotation in the dimensionless form.All steady motion modes of the system have been defined under which a load rotates at a constant angular velocity. In the coordinate system that rotates synchronously to a load, these motions are stationary.Our theoretical study has shown that under motion steady modes:– in the absence of resistance forces in the system, a load rotates synchronously with the rotor;– in the presence of resistance forces in the system, a load is lagging behind the rotor.The load jamming regimes are the one-parameter families of steady motions. Each jamming mode is characterized by the corresponding jam frequency.Depending on the system parameters, one, two, or three possible load jam velocities may exist. If, at any rotor speed, there is only a single angular velocity of a load jam, then the corresponding motion mode (a one-parameter family) is globally asymptomatically steady. If the number of jam velocities varies depending on the angular rotor speed, the asymptomatically steady are:– the only existent mode of jamming (globally asymptomatically steady when there are no others);– jamming modes with the smallest and greatest velocities.A load jam mode with the lowest angular velocity (close to resonance) can be used in order to excite resonance oscillations in vibration machines. The highest frequency of a load jam is close to the rotor speed. This mode can be used to excite the non-resonance oscillations in vibration machine

Experimental Study Into Rotational-oscillatory Vibrations of a Vibration Machine Platform Excited by the Ball Auto-balancer

We have experimentally investigated the rotational-oscillatory vibrations of vibratory machine platform excited by the ball auto-balancer.The law of change in the vibration accelerations at a platform was studied using the accelerometer sensors, a board of the analog-to-digital converter with an USB interface and a PC. The amplitude of rapid and slow vibratory displacements of the platform was investigated employing a laser beam.It was established that the resonance frequency (frequency of natural oscillations) of the platform is: 62.006 rad/s for the platform with a mass of 2,000 gm; 58.644 rad/s ‒ of 2,180 gm; 55.755 rad/s ‒ of 2,360 gm. An error in determining the frequencies does not exceed 0.2 %.The ball auto-balancer excites almost perfect dual-frequency vibrations of a vibratory machine platform. Slow frequency corresponds to the rotational speed of the center of balls around the longitudinal axis of the shaft, while the Fast one ‒ to the shaft rotation speed, with the unbalanced mass attached to it. A dual-frequency mode occurs in a wide range of change in the parameters and it is possible to alter its basic characteristics by changing the mass of balls and the unbalanced mass, the angular velocity of shaft rotation.It has been established experimentally that the balls get stuck at a frequency that is approximately 1 % lower than the resonance frequency of platform oscillations.Assuming the platform executes the dual frequency oscillations, we employed the software package for statistical analysis Statistica to select coefficients for the respective law. It was found that:– the process for determining the magnitudes of coefficients is steady (robust); coefficients almost do no change when altering the time interval for measuring the law of a platform motion;– the amplitude of accelerations due to the low oscillations is directly proportional to the total mass of the balls and the square of the frequency at which balls get stuck;– the amplitude of rapid oscillations is directly proportional to the unbalanced mass at the auto-balancer's casing and to the square of angular velocity of shaft rotation.The discrepancy between the law of motion, obtained experimentally, and the law, obtained using the methods of statistical analysis, is less than 3 %. The results obtained add relevance to both the analytical studies into dynamics of the examined vibratory machine and to the creation of the prototype a vibratory machine

An Increase of the Balancing Capacity of Ball or Roller-type Auto-balancers with Reduction of TIME of Achieving Auto-balancing

The study has revealed an influence of the parameters of corrective weights (balls and cylindrical rollers) in auto-balancers on the balancing capacity and the duration of the transition processes of auto-balancing in Fast-rotating rotors.A compact analytical function has been obtained to determine the balancing capacity of an auto-balancer (for any quantity of corrective weights – balls or rollers), with a subsequent analysis thereof.It is shown that the process of approach of the auto-balancing can be accelerated if the auto-balancer contains at least three corrective weights.It has been proved that at a fixed radius of the corrective weights the highest balancing capacity of an auto-balancer is achieved when the corrective weights occupy nearly half of the racetrack.The study has revealed that it is technically incorrect to formulate a problem of finding a radius of the corrective weights that would maximize the balancing capacity of the auto-balancer. The statement implies that if it is a ball auto-balancer, the racetrack is a sphere, but if it is a roller-type balancer, the racetrack is a cylinder. This leads to a practically useless result, suggesting that the highest balancing capacity is achieved by auto-balancers with one corrective weight. Besides, with n≥5 for balls and n≥8 for rollers, there happens a false optimization, which consists in several corrective weights being “excess”. Their removal increases the balancing capacity of the auto-balancer.It is correct (from the engineering point of view) that the mathematical task is to optimize the balancing capacity of an auto-balancer. Herewith, it is taken into account that the racetrack of the auto-balancer is torus-shaped, which restricts the radius of the corrective weights from the top. It is shown that the balancing capacity of an automatic balancer can be maximized if in a fixed volume the corrective weights have the largest possible radius and occupy almost a half of the racetrack.The research on the duration of the transition processes for the smallest value has produced the following conclusions:– to accelerate the achieving auto-balancing, the corrective weights should occupy nearly half of the racetrack;– the shortest time of the auto-balancing is achieved with three balls or five cylindrical rollers

Methods of Balancing of an Axisymmetric Flexible Rotor by Passive Auto-balancers

The conditions for the occurrence of auto-balancing when balancing a flexible axisymmetric rotor by any number of passive auto-balancers of any type are determined. The problem is actual for the high-speed rotors working at supercritical speeds (rotors of aircraft engines, gas turbine engines of power plants, etc.).The empirical criterion for the occurrence of auto-balancing is applied. Transformations were carried out on the example of the flexible axisymmetric rotor of constant section on two rigid hinge supports. The findings are applicable to rotors with another type of fixing.It is established that auto-balancing of the rotor by n passive auto-balancers located in different correction planes is possible only if the rotor speed exceeds the n-th critical speed. The number of auto-balancers can be arbitrary. Between the critical rotor speeds, additional critical speeds appear. Auto-balancing occurs whenever the rotor passes a critical speed and disappears whenever the rotor passes an additional critical speed.If n auto-balancers are located in the n nodes of the rotor flexural (n+1)-th mode, the j·n-th additional critical rotor speed matches with the j(n+1)-th critical speed, /j=1, 2, 3,…/. When balancing the flexible rotor between the n-th and (n+1)-th critical speeds, such number and placement of auto-balancers are optimum. Auto-balancers at the same time balance the first n distributed modal unbalances and do not respond to the (n+1)-th ones.The additional critical speeds are due to the installation of the auto-balancers on the rotor. Upon transition to them, the behavior of auto-balancers changes. At slightly lower rotor speeds, the auto-balancers reduce the rotor unbalance, and at slightly higher ones – increase it

The Dynamics of A Resonance Single-mass Vibratory Machine with A Vibration Exciter of Targeted Action That Operates on the Sommerfeld Effect

This paper reports a study into the dynamics of a vibratory machine composed of a viscoelastically-fixed platform that can move vertically and two identical inertial vibration exciters. The vibration exciters' bodies rotate at the same angular velocities in opposite directions. The bodies host a single load in the form of a ball, roller, or pendulum. The loads' centers of mass can move relative to the bodies in a circle with a center on the axis of rotation. The loads' relative movements are hindered by the forces of viscous resistance. It was established that a vibratory machine theoretically possesses the following: – one to three oscillatory modes of movement under which loads get stuck at almost constant angular velocity and generate total unbalanced mass in the vertical direction only; – a no-oscillation mode under which loads rotate synchronously with the bodies and generate total unbalanced mass in the horizontal direction only. At the same time, only one oscillatory mode is resonant and exists at the above-the-resonance speeds of body rotation, lower than some characteristic speed. At the bodies' rotation speeds: ‒ pre-resonant; there is a globally asymptotically stable (the only existing) mode of load jams; ‒ above-the-resonance, lower than the characteristic velocity; there are locally asymptotically stable regimes ‒ both the resonance mode of movement of a vibratory machine and a no-oscillations mode; ‒ exceeding the characteristic velocity: there is a globally asymptotically stable no-oscillations mode. Computational experiments have confirmed the results of theoretical research. At the same time, it was additionally established that it would suffice, to enter a resonant mode of movement, to slowly accelerate the bodies of vibration exciters to the above-the-resonance speed, less than the characteristic speed. The results reported here could be interesting both for the theory and practice of designing new vibratory machine