Cancellation Point Research Articles

Upside-Down Logics: Falsification of the Truth and Truthification of the False

This paper is about funny science, recreational mathematics, upside-down thinking, or contradictory reasoning (to think backward). Since a statement in some conditions may be true, in other conditions false, and a third type of conditions partially true and partially false. The paper presents for the first time two types of Upside-Down Logic, the first one is falsification of the Truth (when a true statement is transformed into a false one), and the second one is the opposite: Truthification of the False (when a false statement is transformed into a true one) - within the frame of Recreational Neutrosophy. All transformations from <A> to <antiA> or vice versa should be real, making sense in our real world. Kind of magic logic! Falsification and Truthification are mostly used in the Social Sciences (Anthropology, Archaeology, Economics, Geography, History, Law, Linguistics, Politics, Psychology, Sociology), Philosophy, etc. excelling in Politics:Falsifying the Truth of Enemies[We seek to diminish the enemy's positive side to the point of cancellation and to increase the enemy’s negative side to the point of exaggeration;] and Truthifying the False of the Friends[The opposite: We seek to decrease the friend’s negative side to the point of cancellation, and to increase the friend's positive side to the point of exaggeration.].

Experimental demonstration of thermophones in vibro-acoustic noise cancellation scenario for varying gaseous media

The paper focuses on an analytical and experimental study of global noise cancellation between two co-planar thermo- and vibro-acoustic sources in varying gaseous media. To address the experimental uncertainty in thermophone thermal boundary condition, the previously developed theoretical model is expanded to consider oscillating temperature at the solid-fluid interface, beyond the previously studied oscillating heat flux boundary. The results of the analysis indicate that at the point of optimal cancellation, the ratio of acoustic sources’ powers correlates to the specific heat ratio γ of the surrounding media through γ/(γ−1) relation. Then, a thermophone device is designed using commonly available materials and is deposited on a conventional vibro-acoustic loudspeaker, which acts as the noise source. Both acoustic sources are placed in a sealed acoustic chamber and are experimentally studied in several fluid media with different specific heat ratio values (argon, nitrogen, carbon dioxide and norflurane). The constructive and destructive interferences of the two emitters are analyzed at an exemplary frequency for varying phase differences, and global noise cancellation is demonstrated in all gases using microphone measurements in different spatial locations. The empirical results are observed to fully agree with the theoretical predictions.

A Fully Integrated Passive Self-Jamming Cancellation Architecture with Fast Settling Time for UHF RFID Reader

This paper presents a fully integrated passive self-jamming cancellation (SJC) circuit in 0.18 µm Complementary Metal Oxide Semiconductor (CMOS) technology for ultra-high frequency (UHF) radio frequency identification (RFID) applications. Based on the active amplitude and phase control, a novel passive variable capacitor array and signal combiner are adopted instead of a traditional variable amplifier/attenuator and a phase shifter to reduce the circuit complexity and thus achieve higher linearity and low noise. We use an improved cancellation algorithm based on the local search method to quickly and accurately find the cancellation point that minimizes the self-jamming signal power. The simulation and measurement results are constant, and a suppression of 38 dB can be achieved in the working frequency of 860–960 MHz. The cancellation algorithm can be finished within 0.5 ms. These results indicate that the designed SJC circuit can be a promising candidate for UHF RFID applications.

A Novel Ultrafast Transient Constant on-Time Buck Converter for Multiphase Operation

Constant on-time control (COT) has been widely adopted in buck converters because of its simplicity, fast transient response, and high light-load efficiency. However, the increasing power demands of CPUs and AI/ML engines is pushing voltage regulators to support higher output currents, which typically requires the use of multiphase operation. However, since most high-performance COT schemes utilize ripple as a control variable, the ripple cancellation point in multiphase designs imposes difficult stability concerns, limiting performance, and robustness. In this article, a novel ultrafast transient COT (UFTCOT) control scheme is proposed to enable fast and robust operation even in multiphase converters. The small-signal models of the proposed control scheme are derived based on a describing function technique, whose theoretical results are compared, along with simulation and measurement results, to contrast the proposed UFTCOT technique to exiting approaches.

Active noise control for open windows

Over the last decades, the applications of the active noise control system are broadened. In this study, the active noise control is modeled to reduce the noise pass through an open window. The objective is to define a suitable location for the control sources and error microphones to achieve more noise level reduction at the other side of the window. The performances of the active noise control system are calculated for two different arrangements: (1) the control sources on the edge of the opening and (2) the control sources distributed on the surface of the window. Furthermore, two cost functions are considered to model the noise control system including the minimization of the total squared pressure at cancellation points and the minimization of sound intensity at the surface of the aperture.

Assessing Time-Varying Harmonic Interactions in a Wind Park

The harmonic interaction mechanism in a wind park is examined in this paper. The paper investigates the feasibility of a solution to the yet challenging harmonic contribution estimation from multiple sources in a wind park with limited available information, via an extension of a simple modeling approach as well as from detailed analysis of field measurements. The paper has two distinct objectives in assessing harmonic interactions (a) one to extend the classical Norton equivalent model to a multi-measurement wind park system and to suggest potential areas for further model developments from field measurement analysis, and (b) second to draw inferences from field measurements and to develop a new independent concept of analysis from long-term field measurements in the wind park. From practical experience, a new concept of analysis with a ‘harmonic interaction break-even point’ is introduced. With the help of it, one could identify whether the primary emission (emission from considered source) or secondary emission (emission from a distant source) dominates in the analysis period. In this way, the highest responsibility between different interacting time-varying harmonic sources is evaluated. It was concluded that from long-term measurements one can define a magnitude of power production where a certain harmonic order is canceled or reaches its lowest magnitude. If one finds this cancellation point, one can define a level of secondary/primary emission or at least a feasible range. This knowledge is a step forward towards harmonic contribution analysis.

Inverse Charge Constant On-Time Control With Ultrafast Transient Performance

At the present time, current-mode constant on-time (CMCOT) control is widely used in voltage regulators (VRs) for higher light-load efficiency, higher bandwidth, and a simpler compensation network. In today’s VRs, a high load step with a very high slew rate is a very common requirement in microprocessor or memory applications. One issue of this ripple-based CMCOT control is the transient response limitation at load step-up and step-down, because of its fixed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{\mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> time operation. In the heavy load step-up transient, the inductor current increment becomes limited by the on-time ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{\mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> ) and minimum off-time ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{\mathrm{\scriptscriptstyle OFF}\_{}{\mathrm{ MIN}}}$ </tex-math></inline-formula> ) ratio in each cycle, which can create large undershoot at the output. On the other hand, in the load step-down case, if a load change occurs at the beginning of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{\mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> , then the decrement of the inductor current will be delayed by the fixed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{\mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> width, which can create a large overshoot at output. For the multiphase operation case, this ripple-based CMCOT control fails to operate at the ripple cancellation point where the inductor current ripple becomes zero. The state-of-the-art controllers add various nonlinear controls to the system to solve these issues; however, they are essentially difficult to optimize for different steady-state and transient conditions. In this article, a new concept called ‘inverse charge constant on-time’ (IQCOT) control is proposed, to improve the transient performance in CMCOT, by naturally increasing or decreasing the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{\mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> time in the load step-up or step-down transient without adding any nonlinear control. As this <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{\mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> change is adaptive to the transient requirement, an optimized response is inherently provided, and hence, does not require any external adjustment. In a multiphase operation, IQCOT control can operate seamlessly at the ripple cancellation point. The proposed IQCOT control’s fast and optimized transient response, with higher light-load efficiency, makes it a perfect control candidate for today’s VR applications. Simulation and test results with a VR platform are also presented in this article to verify the benefits of the proposed control.

Adaptive optical self-interference cancellation for in-band full-duplex systems using regular triangle algorithm.

In this paper, we propose an adaptive optical self-interference cancellation using regular triangle algorithm for in-band full-duplex systems. By using this algorithm, the manual adjustment of the tunable optical time delay line and attenuator is replaced with the adaptive program to change the delay and attenuation for achieving optimal cancellation point. The adjustment process is simplified as a convex function problem. We choose to attain the optimal cancellation point by directly and continuously sampling the power of the signal after cancellation and in turn adjust the time delay and attenuation according to the algorithm. In this way, the two paths in the self-interference cancellation system are precisely and automatically matched. By using our proposed algorithm, the interference signal over 300-MHz wideband is diminished to the noise floor, attaining 20-25 dB cancellation depth adaptively. Compared with other existing algorithms in both the experiment and simulation, our proposed regular triangle algorithm reaches the optimal point faster with 10-30% less number of samples from the near start region, and lowers 40-60% less number of samples from the farther start region.

Optimized Switching Sequence for Multiphase Power Converters Under Inductance Mismatch

Multiphase power converters allow to reduce semiconductor stress and to improve total ripple characteristics, when compared to a single-phase converter. Semiconductor stress is reduced by dividing the total current among the N parallel-connected converters or phases. Furthermore, total ripple amplitude is reduced and its frequency increases to N times the switching frequency by interleaving each phase current ripple, which lessens the requirements on the total current filtering. These improvements, however, are detrimented mainly by mismatches among the phase inductors value, leading to different ripple amplitudes among phases. As a consequence, when compared to the ideal case, total ripple amplitude is increased, ripple cancellation points are lost, and switching frequency component and its N $-$ 1 harmonics are generated. This letter proposes a method to mitigate this problem by selecting the phase switching sequence, in converters operating in the continuous conduction mode, which minimizes the switching frequency component and its harmonics in the total ripple. The proposed method efficiently finds the proper switching sequence for any number of phases, by using a previously presented current ripple characterization as the objective function for the optimization procedure. Simulations validate the proposal and show the improvement, when compared to another strategy present in the literature, which uses the switching sequence modification principle.

Active structural acoustic control using the remote sensor method

Active structural acoustic control (ASAC) is an effective method of reducing the sound radiation from vibrating structures. In order to implement ASAC systems using only structural actuators and sensors, it is necessary to employ a model of the sound radiation from the structure. Such models have been presented in the literature for simple structures, such as baffled rectangular plates, and methods of determining the radiation modes of more complex practical structures using experimental data have also been explored. A similar problem arises in the context of active noise control, where cancellation of a disturbance is required at positions in space where it is not possible to locate a physical error microphone. In this case the signals at the cancellation points can be estimated from the outputs of remotely located measurement sensors using the “remote microphone method”. This remote microphone method is extended here to the ASAC problem, in which the pressures at a number of microphone locations must be estimated from measurements on the structure of the radiating system. The control and estimation strategies are described and the performance is assessed for a typical structural radiation problem.

Adaptive feedback active noise control using wavelet frames: simulation and experimental results

Two strategies for adaptive feedback active noise control (ANC) systems are presented here based on wavelet frames. In the first strategy, the noise at the cancellation point is estimated and used as the reference signal in the feedforward ANC system. In the second strategy only the error signal is utilized in the wavelet-based ANC system. The advantages of the second method are: simple structure and less computational load (no need to estimate noise) as well as less sensitivity to the accuracy of estimated secondary path filter. Its disadvantage is high sensitivity to learning rate. To treat this, an adaptive learning rate is proposed to maintain the stability and convergence rate simultaneously. Simulations are carried out for typical linear/nonlinear cases to compare the proposed methods with FxLMS and neural network-based ANC algorithms. Experiments are then conducted to evaluate the developed algorithms. Results show the superior performance of proposed methods in terms of the convergence rate and noise attenuation especially in the presence of an inaccurate identified secondary path filter.

Characterization of Steady-State Current Ripple in Interleaved Power Converters Under Inductance Mismatches

Interleaved power converters are used in high-current applications due to their inherent reduction of semiconductors stress and total ripple. Ripple reduction is accomplished by a correct phase shifting, and the filtering improvement explained by the increase in the ripple frequency. However, these benefits are wasted, among other reasons, by the mismatch of the phase inductor value. As a consequence, differences in the ripple amplitude among phases are produced, leading to a total current ripple significantly greater than the ideal case, the loss of the cancellation points and the generation of the switching frequency component and its harmonics. The works dealing with this subject matter have focused on particular cases, such as a given number of phases, a specific converter topology, or a particular case of inductance mismatch, disregarding a general analytical approach. This paper proposes an analytical method to characterize the total ripple in steady state as a function of the duty cycle and the number of phases under any condition on inductance mismatch. Experimental results validate the proposed method.

Local active noise control using a novel method of designing quiet zones

This paper is concerned with sound minimization in space for local active control in pure tone diffuse fields. Theoretical studies have been performed to develop a new method of designing larger zones of quiet than are obtained with conventional systems. The principle of this new method is to maximize the area of the 10 dB quiet zones. This is in contrast to the conventional design methods, where the acoustic pressure or the acoustic pressure and particle velocity are set to zero at given cancellation points, or the acoustic pressure is minimized over an area using 2-norm and ∞-norm strategies. It is shown that larger zones of quiet are obtained using this new method. The preliminary experiment has also been carried out to validate the simulation results. The main contributions of the paper are that a novel method of designing active systems to generate larger zones of quiet is proposed and the performance of the active systems is analyzed through computer simulations and experiments.

Primary Frequency Standard NPL-CsF2: Optimized Operation Near the Collisional Shift Cancellation Point

We report important modifications introduced to the fountain frequency standard NPL-CsF2, both to its hardware and operation protocol. First, an additional optical pumping stage has been implemented, which has enabled the clock state populations to be efficiently accumulated and has increased the number of detected atoms by a factor of four without affecting the loading and cooling stages. Second, the operation of the fountain near the collisional shift cancellation point has been optimized which, together with the increased atom number, has led to a fourfold reduction in averaging time required to achieve a given statistical resolution, e.g., that matches the type-B uncertainty of NPL-CsF2.

FIVEBRANE STRUCTURES

We study the cohomological physics of fivebranes in type II and heterotic string theory. We give an interpretation of the one-loop term in type IIA, which involves the first and second Pontrjagin classes of spacetime, in terms of obstructions to having bundles with certain structure groups. Using a generalization of the Green–Schwarz anomaly cancellation in heterotic string theory which demands the target space to have a String structure, we observe that the "magnetic dual" version of the anomaly cancellation condition can be read as a higher analog of String structure, which we call Fivebrane structure. This involves lifts of orthogonal and unitary structures through higher connected covers which are not just 3- but even 7-connected. We discuss the topological obstructions to the existence of Fivebrane structures. The dual version of the anomaly cancellation points to a relation of string and Fivebrane structures under electric-magnetic duality.

Discriminating electroweak-ino parameter ordering at the LHC and its impact on LFV studies

Current limit on the dark matter relic abundance may suggest that $|\mu|$ should be smaller than prediction in the minimal supergravity scenario (mSUGRA) for moderate $m_0$ and $m_{1/2}$. The electroweak-ino parameter $M_1, M_2$ and $|\mu|$ are then much closer to each other. This can be realized naturally in the non-universal Higgs mass model (NUHM). Since the heaviest neutralino ($\tilde\chi^0_4$) and chargino ($\tilde\chi^\pm_2$) have significant gaugino components, they may appear frequently in the left-handed squark decay and then be detectable at the LHC. In such a case, we showed that the hierarchy of $M_1, M_2$ and $|\mu|$ can be determined. In the light slepton mass scenario with non-vanishing lepton-flavor violation (LFV) in the right-handed sector, NUHM with small $|\mu|$ corresponds to region of parameter space where strong cancellation among leading contributions to $Br(\mu\to e\gamma)$ can occur. We showed that determination of electroweak-ino hierarchy plays a crucial role in resolving cancellation point of $Br(\mu\to e\gamma)$ and determination of LFV parameters. We also discussed test of the universality of the slepton masses at the LHC and the implications to SUSY flavor models.

Lessons from Evidence-Based Operating Room Management in Balancing the Needs for Efficient, Effective and Ethical Healthcare

Foglia et al. (in press) describe tension in two veteran's hospitals among managers, clinicians, and patients over allocating appropriate resources to support care and inefficiencies in care delivery. Ultimately ethical healthcare in a system which is committed to caring for an entire population of patients must use its limited resources effectively while not compromising patient safety. This discussion gives examples from operating room management in which systematic analyses of existing data can guide more efficient care delivery. The VA Healthcare system is committed to serving an entire population of patients. This mission leads to ethical dilemmas around using limited funds to ensure that each patient who needs care receives it in a safe and timely manner. Focus groups conducted on managers, clinicians, ethics committee chairs, and patients/veterans in two VA medical centers revealed discrepancies in the ethical challenges they faced (Foglia et al, in press). Three of the groups described tension over allocating appropriate resources to support care. Managers felt resource allocation was often arbitrary and they were compelled to follow political pressures rather than clinical service needs. Clinicians felt tension between rendering high quality services in an institution with limited resources and where patients sometimes pressured them to render unnecessary care. Patients felt disrespect from clinicians because they endured long waits for care and sometimes came for appointments that were delayed to the point of cancellation. Ultimately ethical healthcare in a system which is committed to caring for an entire population of patients must use its resources effectively while not compromising patient safety. Asking stakeholders to take action to improve efficiency in care from a hospital perspective demands an evaluation of whether these actions actually move toward the intended system goals. Incorporating principles of evidence-based management enables a pragmatic approach to effective resource allocation and provides this evaluative process.

Substrate Noise Cancellation Circuit Using Cancellation Points

A substrate noise cancellation circuit using cancellation points is proposed. Noise characteristic of a conventional cancellation circuit with divided points is analytically explained. A new version of active cancellation circuit with some points removed is proposed. Noise reduction of this version of active cancellation circuits is confirmed by computer simulations. Simulation and experimental results show using two cancellation points effectively reduces the noise.

Necessary and Sufficient Conditions for Perfect Command Following and Disturbance Rejection in Fractional Order Systems

The aim of this paper is to present a modified explanation of the classic internal model principle for certain class of finite-dimensional, time-invariant, deterministic fractional-order systems commonly known as fractional systems of commensurate order. The necessary and sufficient conditions for perfect command tracking and disturbance rejection are provided. The difficulty of applying the classic internal model principle to fractional-order systems is due to the difference between integer-order and fractional-order systems from the zero-pole cancellation point of view. The notion of zero-pole cancellation is discussed for the systems under consideration in a well posed mathematical framework. It is also shown that fractional elements can be used for command tracking and disturbance rejection purposes which provides more flexibility for controller design applications. Two illustrative examples confirm the applicability of the proposed theorems.

Computationally Efficient Partial Crosstalk Cancellation in Fast Time-Varying DSL Crosstalk Environments

Line selection (LS), tone selection (TS), and joint tone-line selection (JTLS) partial crosstalk cancellers have been proposed to reduce the online computational complexity of far-end crosstalk (FEXT) cancellers in digital subscriber lines (DSL). However, when the crosstalk profile changes rapidly over time, there is an additional requirement that the partial crosstalk cancellers, particularly the LS and JTLS schemes, should also provide a low preprocessing complexity. This is in contrast to the case for perfect crosstalk cancellers. In this paper, we propose two novel channel matrix inversion methods, the approximate inverse (AI) and reduced inverse (RI) schemes, which reduce the recurrent complexity of the LS and JTLS schemes. Moreover, we propose two new classes of JTLS algorithms, the subsort and Lagrange JTLS algorithms, with significantly lower computational complexity than the recently proposed optimal greedy JTLS scheme. The computational complexity analysis of our algorithms shows that they provide much lower recurrent complexities than the greedy JTLS algorithm, allowing them to work efficiently in very fast time-varying crosstalk environments. Moreover, the analytical and simulation results demonstrate that our techniques are close to the optimal solution from the crosstalk cancellation point of view. The results also reveal that partial crosstalk cancellation is more beneficial in upstream DSL, particularly for short loops.