a b s t r a c tThis paper deals with the problem of optimal decentralized power control in systems whose spectrum is regulated in time and space, the so-called time-area-spectrum (TAS) licensed. In this paper we consider those locations with colliding transmissions; thus, addressing a scenario with full interference. In order to facilitate the coexistence of different TAS licenses, the power spectral density of the used band shall be limited. Since controlling the overall radiated power in a given area is cumbersome, we control the amount of received power. First, we present the achievable rates (i.e. the rate Pareto set) and their corresponding powers by means of multi-criteria optimization theory. Second, we study a completely decentralized and gradient-based power control that obtains Pareto-efficient rates and powers, the so-called DPC-TAS (Decentralized Power Control for TAS). The power control convergence and the possibility of guaranteeing a minimum Quality of Service (QoS) per user are analyzed. Third, in order to gain more insight into the features of DPC-TAS, this paper compares it with other baseline power control approaches. For the sake of comparison, a simple pricing mechanism is proposed. Numerical simulations verify the good performance of DPC-TAS.

Motion control has been one of the main areas of focus for the development of residual vibration reduction. Its application has been widely addressed to cranes [1][2][3][4] . Extensive work has been carried out within the methods based on command generation techniques applied to discrete linear systems 5,6 : In general, the state of the flexible modes at the initial condition is considered to be null, such as in the rest-to-rest maneuvers. This is the case of a standard crane. Most of its maneuvers, that include an input shaper in its control, will start in a null initial oscillatory condition and will achieve a null residual vibration in the stationary state. However, if there is a requirement of an emergency stop while the payload is swaying during the transient, the motion profile which is generated in a standard condition does not guarantee the stop of this load with a null residual oscillation. The main objective of the current development is to provide a method to design input functions which includes the non-zero initial states of the system in its formulation and to focus on a real time application such as an emergency stop of a crane. The new method can be included within the time-domain approaches. Other literature methods among the before mentioned time-domain approaches are the signal generation by means of trigonometric series and the so-called input shapers which are the most commonly used; other methods base their formulation in the frequency-domain, such as command conventional filtering and zero-placement techniques. Within the time-domain techniques, early approaches [7][8][9] focused the definition of the transient motion profiles through trigonometric series expansion avoiding the terms related with the system natural frequency. Another technique defines the motion profiles through convolution of pulses multiplied by a negative exponential time function when damping is considered 10,11 .The zero-vibration (ZV) input shaper was firstly proposed in 1950 12 and developed later [13][14][15] : an input signal is shaped by convolving it with two impulses, properly located in time and with the appropriate amplitude. The vibration that is generated with the first impulse is suppressed with the vibration which is generated with the second one. This property remains invariable when any command signal is convolved with this impulse sequence. To provide robustness against variation of the system parameters, the zero-vibration and derivative (ZVD) and extra insensitive (EI) shapers were designed by adding one more impulse to the ZV shaper. Other approaches of this technique included: i) phasorial diagrams to reduce numerical calculations 16,17 ; ii) negative impulses to reduce the transient time 18 ; iii) an optimal trade-off between performance, measured in terms of residual vibration and speed, and robustness 19 ; iv) the cancellation of a so-called pseudo-mode with lower frequency than any of the system component modes 20 ; v) the reduction of the system response during the transient 21,22 .Frequency do...

This paper presents an adaptive algorithm to reduce residual vibrations when the feedback sensor used has the drawback of having null drift along the time. The adaptive approaches are useful to deal with large variations of the system parameters at each maneuver, such as it occurs in cranes. For the feedback sensor, the use of inertial measurement units such as Micro-Electro-Mechanical Systems (MEMS) is increasingly extended because of their cost, size, robustness and power consumption. However, the effectiveness of the adaptive input shaping algorithms is compromised because of this drift, which is a commonly raised issue in this kind of devices. For a standard crane application, this major drawback could be avoided with a frequent time-basis calibration of the sensor, but it is not a feasible solution. The study presented in this manuscript focuses on the development of an automatic compensation of this drift to obviate such frequent calibrations. It is based on a non-asymptotic algebraic identification technique, which has the advantage of not requiring initial conditions and having a short convergence time. The new formulation uses the Zero-Vibration (ZV) input shaper technique, and the null drift is added to the algorithm as a new parameter to be identified. The proposed method has been particularized for single maneuvers of cranes with a gyroscope as feedback sensor, in a real time scenario. Experimental results show the efficacy of the method with its application to a scaled crane test platform. P R E -P R I N T V E R S I O N

Due to dynamic effects, clearances, manufacturing and assembly errors in form-closed cam mechanisms, the follower jump can also occur. For conjugate cam mechanisms a technique to avoid the follower jump without the use of a spring involves making the conjugate cam profiles bigger than the kinematical ones by adding an external offset. This strategy produces an interference fit between the conjugate cam profiles and the follower train. This paper presents an ordered procedure to study the influence that the planned interference fit has on the evaluation of the contact forces, the expected fatigue life of the rollers, contact pressures and the lubrication conditions. The study is based on a conjugate cam mechanism with translational roller followers used in a real automatic process for manufacturing muselets. A three-degree-of-freedom dynamic model is proposed and the Hertzian theory for general profiles is used to model the nonlinear contact stiffness between the cams and the crowned rollers. The dynamic model predicts that it is difficult to obtain conjugate cam mechanisms with an infinite expected fatigue life of the rollers just by considering typical achievable manufacturing errors or clearances, and as happens in reality, a set-up process is highly recommended. The procedure is also tested with measured manufacturing errors on a coordinate measure machine—CMM—and with measured radial internal clearances for the rollers measured by an experimental apparatus. Also, to evaluate lubrication conditions, surface finishing measurements have been taken of the cams and the rollers with a surface profiler.

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