Dynamic Squeeze Research Articles

Improving predictions of rock tunnel squeezing with ensemble Q-learning and online Markov chain

Predicting rock tunnel squeezing in underground projects is challenging due to its intricate and unpredictable nature. This study proposes an innovative approach to enhance the accuracy and reliability of tunnel squeezing prediction. The proposed method combines ensemble learning techniques with Q-learning and online Markov chain integration. A deep learning model is trained on a comprehensive database comprising tunnel parameters including diameter (D), burial depth (H), support stiffness (K), and tunneling quality index (Q). Multiple deep learning models are trained concurrently, leveraging ensemble learning to capture diverse patterns and improve prediction performance. Integration of the Q-learning-Online Markov Chain further refines predictions. The online Markov chain analyzes historical sequences of tunnel parameters and squeezing class transitions, establishing transition probabilities between different squeezing classes. The Q-learning algorithm optimizes decision-making by learning the optimal policy for transitioning between tunnel states. The proposed model is evaluated using a dataset from various tunnel construction projects, assessing performance through metrics like accuracy, precision, recall, and F1-score. Results demonstrate the efficiency of the ensemble deep learning model combined with Q-learning-Online Markov Chain in predicting surrounding rock tunnel squeezing. This approach offers insights into parameter interrelationships and dynamic squeezing characteristics, enabling proactive planning and support measures implementation to mitigate tunnel squeezing hazards and ensure underground structure safety. Experimental results show the model achieves a prediction accuracy of 98.11%, surpassing individual CNN and RNN models, with an AUC value of 0.98.

DSNet: A dynamic squeeze network for real-time weld seam image segmentation

The image noise generated by the welding process, such as arc light, splash, and smoke, brings significant challenges for the laser vision sensor-based welding robot to locate the weld seam and accurately conduct automatic welding. Currently, deep learning-based approaches surpass traditional methods in flexibility and robustness. However, their significant computational cost leads to a mismatch with the real-time requirement of automated welding. In this paper, we propose an efficient hybrid architecture of Convolutional Neural Network (CNN) and transformer, referred to as Dynamic Squeeze Network (DSNet), for real-time weld seam segmentation. More precisely, a lightweight segmentation framework is developed to fully leverage the advantages of the transformer structure without significantly increasing computational overhead. In this respect, an efficient encoder, which aims to increase its features diversity, has been designed and resulted in substantial improvement of encoding performance. Moreover, we propose a plug-and-play lightweight attention module that generates more effective attention weights by exploiting statistical information of weld seam data and introducing linear priors. Extensive experiments on weld seam images using NVIDIA GTX 1050Ti show that our approach reduces the number of parameters by 54x, decreases computational complexity by 34x, and improves inference speed by 33x compared to the baseline method TransUNet. DSNet achieves superior accuracy (78.01% IoU, 87.64% Dice) and speed performance (100 FPS) with lower model complexity and computational burden than most state-of-the-art methods. The code is available at https://github.com/hackerschen/DSNet.

Impact of Early Coherences on the Control of Ultrafast Photodissociation Reactions.

By coherent control, the yield of photodissociation reactions can be maximized, starting in a suitable superposition of vibrational states. In ultrafast processes, the interfering pathways are born from the early vibrational coherences in the ground electronic potential. We interpret their effect from a purely classical picture, in which the correlation between the initial position and momentum helps to synchronize the vibrational dynamics at the Franck-Condon window when the pulse is at its maximum intensity. In the quantum domain, we show that this localization in time and space is mediated by dynamic squeezing of the wave packet.

Application of Dynamically Search Space Squeezed Modified Firefly Algorithm to a Novel Short Term Economic Dispatch of Multi-Generation Systems

The absence of the global best component in the update equation of the conventional firefly algorithm degrades its exploration properties. This research proposes multi-update position criteria to enhance the exploration properties of the conventional firefly technique while including the effect of the global best solution on the movement of the fireflies in the search space of the objective function. Moreover, the dynamic search space squeezing is applied to constrict the movement of the fireflies within the certain limits to avoid their oscillatory movement as the solution approaches towards the global best by determining the optimal trajectory for each firefly. The robustness of the suggested firefly algorithm is tested on a hybrid energy system consisting of thermal, hydroelectric, and Photovoltaic (PV) energy source. The intermittent nature of the PV energy source is explained using fractional integral polynomial model and Auto Regressive Integrated Moving Average (ARIMA) model. The main dispatch problem is successfully computed using both the modified firefly and the simple firefly algorithm by determining the optimal power share of each energy source for different scheduling intervals. The suggested operational strategy reduces the overall generation cost of the system while preserving the various system constraints. Due to the stochastic nature of the meta-heuristic techniques, the two suggested algorithms are compared statistically for different test cases using the independent t-test results. The statistical comparison suggests that the performance of the modified firefly is superior to its conventional counterpart as the evaluation parameters of the modified firefly converge to relatively lower value as compared to the parameters of the simple firefly algorithm.

Dissipative bosonic squeezing via frequency modulation and its application in optomechanics.

The dissipative squeezing mechanism is an effective method to generate the strong squeezing, which is important in the precision metrology. Here, we propose a practical method to achieve arbitrary bosonic squeezing via introducing frequency modulation into the coupled harmonic resonator model. We analyze the effect of frequency modulation and give the analytical and numerical squeezing results, respectively. To measure the accurate dynamic squeezing in our proposal, we give a more general defination of the relative squeezing degree. Finally, the proposed method is extended to generate the strong mechanical squeezing (>3 dB) in a practical optomechanical system consisting of a graphene mechanical oscillator coupled to a superconducting microwave cavity. The result indicates that the strong mechanical squeezing can be effectively achieved even when the mechanical oscillator is not initially in its ground state. The proposed method expands the study on nonclassical state and does not need the bichromatic microwave driving technology.

A high-throughput microfluidic device for probing calcium dynamics of single cells squeezing through narrow channels

To probe intracellular calcium response while single cells squeeze through narrow channels, we built a high-throughput microfluidic device where single cells can be trapped efficiently and stimulated mechanically. With this device, dozens of single cells’ dynamic morphologies and intracellular [Ca2+] responses under dynamic mechanical stimuli can be monitored simultaneously. We observed a two-peak [Ca2+] response, which was closely coupled together with the dynamic cellular squeezing process. This type of [Ca2+] response, to our knowledge, was observed for the first time. We also investigated the role of the cytoskeleton in the [Ca2+] response and found that the cytoskeleton was an important regulator of [Ca2+] signaling during the cellular squeezing process. In addition, we investigated the difference between the two-peak [Ca2+] responses of Hela cells and HUVECs and found that one characteristic parameter could distinguish Hela cells from HUVECs.

Statistical Performances Evaluation of APSO and Improved APSO for Short Term Hydrothermal Scheduling Problem

The Accelerated Particle Swarm Optimization (APSO) algorithm is an efficient and the easiest to implement variant of the famous Particle Swarm Optimization (PSO) algorithm. PSO and its variant APSO have been implemented on the famous Short-Term Hydrothermal Scheduling (STHTS) problem in recent research, and they have shown promising results. The APSO algorithm can be further modified to enhance its optimizing capability by deploying dynamic search space squeezing. This paper presents the implementation of the improved APSO algorithm that is based on dynamic search space squeezing, on the short-term hydrothermal scheduling problem. To give a quantitative comparison, a true statistical comparison based on comparing means is also presented to draw conclusions.

Atom-assisted quadrature squeezing of a mechanical oscillator inside a dispersive cavity

We present a hybrid optomechanical scheme to achieve dynamical squeezing of position quadrature of a mesoscopic mechanical oscillator, that can be externally controlled by classical fields. A membrane-in-the-middle set up is employed, in which an atom in $\Lambda$ configuration is considered to be trapped on either side of the membrane inside the cavity. We show that a considerable amount of squeezing (beyond the 3 dB limit) can be achieved that is not affected by the decay of the cavity and the spontaneous emission of the atom. Squeezing depends upon the initial preparation of atomic states. Further, a strong effective coupling between the atom and the oscillator can be attained by using large control fields that pump the atom and the cavity. Effect of thermal phononic bath on squeezing is studied in terms of the squeezing spectrum. The results are supported by the detailed analytical calculations.

Characteristics of magnetorheological fluids under single and mixed modes

Rheological properties of magnetorheological (MR) fluids can be changed by application of external magnetic fields. These dramatic and reversible field-induced rheological changes permit the construction of many novel electromechanical devices having potential utility in the automotive, aerospace, medical and other fields. Vibration control is regarded as one of the most successful engineering applications of magnetorheological devices, most of which have exploited the variable shear, flow or squeeze characteristics of magnetorheological fluids. These fluids may have even greater potential for applications in vibration control if utilised under a mixed-mode operation. This article presents results of an experimental investigation conducted using magnetorheological fluids operated under dynamic squeeze, shear-flow and mixed modes. A special magnetorheological fluid cell comprising a cylinder, which served as a reservoir for the fluid, and a piston was designed and tested under constant input displacement using a high-strength tensile machine for various magnetic field intensities. Under vertical piston motions, the magnetorheological fluid sandwiched between the parallel circular planes of the cell was subjected to compressive and tensile stresses, whereas the fluid contained within the annular gap was subjected to shear flow stresses. The magnetic field required to energise the fluid was provided by a pair of toroidally shaped coils, located symmetrically about the centerline of the piston and cylinder. This arrangement allows individual and simultaneous control of the fluid contained in the circular and cylindrical fluid gaps; consequently, the squeeze mode, shear-flow mode or mixed-mode operation of the fluid could be activated separately. The performance of these fluids was found to depend on the strain direction. Additionally, the level of transmitted force was found to improve significantly under mixed-mode operation of the fluid.

Dynamical Two-Mode Squeezing of Thermal Fluctuations in a Cavity Optomechanical System.

We report the experimental observation of two-mode squeezing in the oscillation quadratures of a thermal micro-oscillator. This effect is obtained by parametric modulation of the optical spring in a cavity optomechanical system. In addition to stationary variance measurements, we describe the dynamic behavior in the regime of pulsed parametric excitation, showing an enhanced squeezing effect surpassing the stationary 3dB limit. While the present experiment is in the classical regime, our technique can be exploited to produce entangled, macroscopic quantum optomechanical modes.

Experimental realization of a dynamic squeezing gate

Squeezing is a nonlinear Gaussian operation that is the key component in construction of other nonlinear Gaussian gates. In our implementation of the squeezing gate, the amount and the orientation of the squeezing can be controlled by an external driving signal with 1 MHz operational bandwidth. This opens a brand new area of dynamic Gaussian processing. In particular, the gate can be immediately employed as the feed-forward needed for the deterministic implementation of the quantum cubic gate, which is a key piece of universal quantum information processing.

Parametric competition in non-autonomous Hamiltonian systems

In this work we use the formalism of chord functions (i.e. characteristic functions) to analytically solve quadratic non-autonomous Hamiltonians coupled to a reservoir composed by an infinity set of oscillators, with Gaussian initial state. We analytically obtain a solution for the characteristic function under dissipation, and therefore for the determinant of the covariance matrix and the von Neumann entropy, where the latter is the physical quantity of interest. We study in details two examples that are known to show dynamical squeezing and instability effects: the inverted harmonic oscillator and an oscillator with time dependent frequency. We show that it will appear in both cases a clear competition between instability and dissipation. If the dissipation is small when compared to the instability, the squeezing generation is dominant and one can see an increasing in the von Neumann entropy. When the dissipation is large enough, the dynamical squeezing generation in one of the quadratures is retained, thence the growth in the von Neumann entropy is contained.

The Sonographic Squeeze Test: Assessing the Reliability of the Dorsal Scapholunate Ligament

There is no universally accepted imaging method to diagnose scapholunate ligament (SLL) tears. Our aim was to use sonography to evaluate the reliability of SLL length at baseline compared with a standardized dynamometer maneuver in healthy normals. Sonographic exams from 31 consented asymptomatic patients between 18 years and 45 years of age were collected on a total of 60 wrists. The length of the SLL was measured superficially and at a depth of 3.0 mm during static and dynamic squeeze maneuver. Inter- and intraexaminer reliability was performed using the intraclass correlation coefficient (ICC). The superficial ligament length measured 0.60 cm ± 0.11 cm with a deep measurement of 0.20 cm ± 0.06 cm. Dynamic evaluation revealed superficial and deep measurements at 0.62 ± 0.12 cm and 0.20 ± 0.06 cm, respectively. There was no significant difference between the SLL length at rest and during the squeeze test. The interexaminer and intraexaminer reliability was rated at fair to very good. The evaluation of the dorsal SLL by sonographic squeeze test is reliable. Future studies will apply this method to suspected SLL tears.

Rheological characterization of poly(ethylene oxide) aqueous solution under dynamic helical squeeze flow

Oscillatory shear flow has been widely used to investigate the flow properties of a wide range of complex fluids. The flow is useful because experimental platform is already fixed and its analysis has sound theoretical background. However it is too simple compared to the complex flows encountered in industry. Accordingly, the rheological response of complex fluids needs to be investigated in more complicated flow field. There were several reports on the superimposed flows in which oscillatory flow was applied either parallel or perpendicular to the steady shear flow. In this paper, we propose dynamic helical squeeze flow (DHSQ) which superimposes oscillatory shear and oscillatory squeeze between parallel plates. The nonlinear response in DHSQ was studied by comparing DHSQ with oscillatory shear (OS) and with oscillatory squeeze (OSQ) in terms of stress shape and Lissajous plot. In DHSQ, both stress curve and Lissajous plot of shear and normal stresses showed nonsymmetric characteristics unlike shear stress in large amplitude oscillatory shear (LAOS). The normal stress in DHSQ was more distorted than that of OSQ. The shear stress in DHSQ showed the onset of nonlinearity at lower strain amplitude than that of oscillatory shear flow (OS). It is due to the coupling of shear and squeeze flows, and the effect was more pronounced in the shear stress than in the normal stress.

Dynamic search space squeezing strategy based intelligent algorithm solutions to economic dispatch with multiple fuels

This paper presents a new approach to the solution of optimal power generation for economic dispatch (ED) using improved particle swarm optimization (IPSO) technique. In this paper an improved PSO technique is suggested that deals with equality and inequality constraints in ED problems. A constraint treatment mechanism called dynamic search space squeezing strategy is devised to accelerate the optimization process and simultaneously the dynamic process inherent in the conventional PSO algorithm is preserved. The application and statistical performance of various intelligent algorithms such as differential evolution (DE), particle swarm optimization (PSO) and improved particle swarm optimization (IPSO) are considered on economic dispatch problems with non-smooth cost functions considering valve point effects and multiple fuel options. To determine the efficiency and effectiveness of various intelligent algorithms, three experiments are conducted considering only multiple fuel options, considering both valve-point and multiple fuel options and also taking into account the valve point loadings, ramp rate limits and prohibited operating zones. The simulation results reveal that the proposed IPSO has provided the better solution with a very high probability to demonstrate its robustness over other intelligent techniques such as DE, PSO and improved genetic algorithm with multiplier updating (IGA_MU), ant colony optimization (ACO), artificial bee colony algorithm (ABC), hybrid swarm intelligent based harmony search algorithm (HHS) and fuzzy adaptive chaotic ant swarm optimization (FCASO). The proposed IPSO ensures convergence within least execution time and provides quality solutions as compared to earlier reported best results.

A new instrument for dynamic helical squeeze flow which superposes oscillatory shear and oscillatory squeeze flow

Simple shear flow has been widely used as a model flow system to investigate the rheological properties of complex fluids. Although it is useful and easy to apply, the shear flow is too simple compared with the complicated flows encountered in real processes. For this reason, it is necessary to study the rheological properties of viscoelastic fluids subjected to more complicated flow field. In this paper, we report a new instrument in which dynamic helical squeeze flow is generated. It superimposes the oscillatory squeeze flow on the oscillatory shear flow, and was designed to get more information on the microstructural change of complex fluids in the flow field which is more complex than conventional simple shear but is still well-defined. This instrument has advantages: the shear and normal stresses can be obtained simultaneously under the coupled flow field; the present design can be used to investigate the structural anisotropy in the direction of both rotational and vertical motion. This study provides a new design and methodology to investigate the rheological responses of complex fluids under dynamic helical squeeze flow.

Design and Performance Evaluation of Magnetorheological Fluids Under Single and Mixed Modes

Magnetorheological (MR) fluids are capable of providing continuously variable damping forces in response to a magnetic stimulus. Most MR devices have exploited the variable shear or flow characteristics of MR fluids. Greater potential application in vibration control/isolation may be sought if these fluids are utilized in the squeeze mode in which displacement levels are limited to few millimeters, but large force levels are available. In this article, the results of an experimental assessment of the comparative performance of MR fluids in dynamic squeeze, shear-flow, and mixed modes are presented. A mixed-mode MR cell comprising a cylinder which provides the reservoir for the fluid and a piston was designed and fabricated. The cylinder is subjected to an oscillatory sinusoidal motion while the piston is fixed. This motion simultaneously subjects the fluid sandwiched between the parallel circular-planes of the cell to compressive and tensile loadings, and the fluid contained in the cylindrical gap to a combined shear and flow loading. The magnetic field required to energize the fluid is provided by a pair of toroidally shaped coils, disposed symmetrically about the cylinder/piston centreline. This arrangement permits a separate excitation of the fluid contained in the circular or cylindrical gaps to simulate either a squeeze mode or a shear-flow mode, respectively, in addition to a simultaneous excitation of the fluid to simulate a mixed squeeze and shear-flow mode. The cell was tested under various loadings and magnetic field intensity conditions. Comparisons between the different modes of operation were carried out and the transmitted force level was seen to be greatly enhanced when the fluid was employed under the mixed mode. In addition, the implications of the results to vibration control, where MR fluids are utilized in short-stroke damping applications, are discussed.

Phenomenological modeling of the response of a dense colloidal suspension under dynamic squeezing flow

The split Hopkinson pressure bar experimental technique is used to evaluate the squeezing flow response of a concentrated, discontinuously thickening colloidal suspension of spherical silica particles loaded at high stresses/strain rates. These results provide insight into the transitional behavior of these materials, as well as the post-transitional response under compressive loading. A method of analyzing the strain and strain rate dependent behavior is presented to identify modes of material response (viscous, elastic, etc.). Experimental results are presented as stress–strain–strain rate plots and a surface fitting approach is used to develop a phenomenological model describing the overall response. From this model, it is possible to identify regions of elastic and viscous behavior using a gradient analysis approach. It was found that, after an initial period of viscous deformation, the suspension behaves like a viscoelastic material – this regime corresponds well with transition in which large clusters of particles percolate. This is followed by a third, viscous regime in which the material undergoes viscous deformation. At the highest stresses, a plateau region of plastic deformation has been identified. This approach and the conditions under which it may be applied are described in detail in the paper.

The influence of solid-phase concentration on the performance of electrorheological fluids in dynamic squeeze flow

The yield stress of electrorheological (ER) fluids increases by orders of magnitude when electric field is applied across them. In the absence of the field, ER fluids behave as Newtonian fluids. This paper is concerned with an experimental investigation to determine the rheological performance of ER fluids, consisting of a dielectric liquid carrier with a range of solid-phase concentration. The ER fluid was contained in a squeeze cell, which during motion subjects the fluid to both compressive and tensile loading. The results were analysed in terms of the capacity for the transmission of imposed forces across the fluid and showed a great dependence on the applied D.C voltage and the weight fraction of the dispersed solid-phase. In addition, the implications of the results to vibration control, where the ER fluid is employed in an engine mount, are discussed.

Eigenstates of the higher powers of an annihilation operator for a time-dependent harmonic oscillator and their properties

In the framework of dynamical invariant theory, we introduce the annihilation operator and creation operator for a time-dependent harmonic oscillator. The orthonormalized eigenstates of the operator are constructed, and their mathematical and quantum statistical properties are discussed in detail. Specifically, a particle moving in a Paul trap with periodically varying frequency is treated as an example to demonstrate the dynamical squeezing effects for the eigenstates of the operator .