Pneumatic Generator Research Articles

Innovation in Green Materials for the Non-Contact Stabilization of Sensitive Works of Art: Preliminary Assessment and the First Application of Ultra-Low Viscosity Hydroxypropyl Methylcellulose (HPMC) by Ultrasonic Misting to Consolidate Unstable Porous and Powdery Media

Paintings and other works of art created with fragile and mechanically unstable powdery media present challenges to conservators. Frequently, powdery media is water-sensitive, extremely fragile, tends to delaminate, and may be altered by even the slightest physical action or interaction with liquids. Materials that can provide an efficient stabilization without unacceptably altering the optical characteristics of the delicate substrate are extremely limited. Among these, Funori, Isinglass, and Methocel A4C have become established for this use. In bench practice, consolidants are frequently applied in a non-contact way, using ultrasonic and pneumatic aerosol generators to minimize the impact of the consolidant on sensitive substrates. However, nebulizing the available materials is problematic in bench practice, because of their high viscosity and, only extremely low concentrations can be nebulized using low kinetic impact ultrasonic or pressure-based misting systems adopted from the healthcare industry. As a potential innovative solution, this study introduces novel ultra-low viscosity (ULV) cellulose ethers (ULV-HPMC) for stabilisation of unstable porous and powdery surfaces, which have been successfully applied in bench practice for the pilot treatment of Edvard Munch painting on canvas and two 19th c. Thai gouache paintings on panel. Novel ULV-HPMC materials have multiple desirable qualities for consolidation treatments in conservation, and in accelerated aging tests marginally outperformed Methocel A4C, considered to be one of the most stable consolidants in the practice of conservation. Because of the ultra-low viscosity, higher concentrations of ULV-HPMC materials can be applied as water-based aerosols in a non-contact way and in fewer applications, which is a significant advantage in the treatment of delicate water-sensitive surfaces. Notably, novel ULV biopolymers are low-cost, derive from sustainable and renewable sources, and do not raise health and environmental concerns. Such novel materials and methods seamlessly resonate with the ICOM-CC’s Melbourne 2014 declaration, EU Green Deal, and the UN’s Sustainable Development goals and show potential adding new sustainable materials with the exceptionally low viscosity to the conservator’s tool box.

Simulation of a metal pellet spraying generator driven by micro-air pressure

Molten metal droplet techniques are one of the important technologies for printing micro-metal parts. At present, the equipment developed for this technology faces some challenges, such as the requirement for a micro-oxygen environment during operation and a complicated manufacturing process. Consequently, a micro-air-pressure driven metal pellet spraying (MPS) 3D printing generator was designed and manufactured using the drop-on-demand technique, which uses simple and low-cost equipment in an atmospheric environment. A 2D axisymmetric model has been proposed to study the mechanism of droplet generation by using a micro-pneumatic MPS generator. In addition, a proprietary pneumatic MPS generator was also used to conduct droplet generation experiments. The validity of the proposed model was verified through the simulation results of the droplet pattern and droplet diameter, which were in good agreement with the experimental ones. The analysis shows that in the droplet injection forming process, surface tension is dominant for low viscosity liquids at a very small Ohnesorge number (Oh < 0.01). The surface tension was conducive to the maintenance of the molten form of the projectile. During droplet injection, the phenomenon of oblate–prolate oscillation occurs due to the non-uniform distribution of pressure inside the droplet. This phenomenon exerts an influence on the accuracy of the droplet flight trajectory and deposition position. This study serves as a good reference for selecting the suitable settings for producing metal droplets using the MPS generator.

A Design Model for Electric Environmental Control System in Aircraft Conceptual and Preliminary Design

In present decades, the need for a more efficient air transport system is driving towards more electric aircraft subsystems. Electrified subsystems offer the opportunity to optimize the operational performance of systems by reducing the power required by the propulsion system therefore, reducing the fuel burnt. A considerable advantage can be obtained by electrifying the environmental control system which is the most power demanding aircraft subsystem. The paper presents a simplified model to estimate the main performances of the conventional and electrified environmental control system during the aircraft conceptual and preliminary design phases. Different air cycle machine architectures can be designed. The model is divided in two main modules. The first is dedicated to the estimation of the aircraft thermal loads including the effect of solar radiation, the conduction of external air, the presence of passengers and the avionic systems. With the main result of estimating the cabin airflow required to control the temperature and the air quality within the aircraft’s mission profile. The second module of the model designs all major components of the air conditioning pack including the dedicated compressors of the electrified environmental control system. The model requires basic input data that can be easily estimated during the early stages of aircraft design. The model is calibrated using the available data of a conventional system and then applied to the electrified one. The results show the increased efficiency of the electrified system that results from optimizing both pneumatic power generation and the air cycle machine.

Large-scale experiments on tsunami inundation and overtopping forces at vertical sea walls

Tsunami are very long gravity waves that may cause significant damage to coastal sea walls. The majority of relevant design codes and research papers that describe methods for predicting tsunami loads on coastal walls consider the scenario of transitory force from a bore-led wave. This does not relate to tsunami that do not form bore waves. Bore fronts generally cause short term spikes in force, which may have little effect on the vulnerability of massive structures. Post disaster accounts suggest that most coastal walls show damage that implies failure modes that occur over moderate to long durations. Therefore it is likely that the bore front assumption gives an overly conservative prediction of maximum force, and may not capture the full timescale of tsunami loading. This paper uses a pneumatic tsunami generation facility to determine the force loading on two vertical coastal sea walls during tsunami inundation. Two sea-wall models, 0.15 and 0.25 m high, with crown widths of 0.1 m (7.5 and 12.5 m at a nominal prototype scale of 1:50) are tested. It is shown that bore fronts only occur for short period waves over the bathymetry tested. Bore fronts cause a very short period spike in force, which is followed by a transitory force approximated by the hydrostatic pressure equation. The loading of tsunami length waves of periods ≥ 40 s (280 s prototype at 1:50 scale), which do not break is not greater than 1.2 times the hydrostatic force. Overtopping volume is positively correlated to the time duration of positive upstream head over the crest, rather than its maximum value. Overtopping causes a small increase in the horizontal load due to the addition of a drag and momentum load. The magnitude and time of these effects are small and short-lived in comparison to the hydrostatic load. The results compare well with available equations based on hydrostatic force and the engineer may apply a desired multiplying coefficient of a factor of at least 1.2 to account for any added pressure and momentum, and the factor of safety intended. • Tsunami loads on vertical walls are no greater than 1.2 times the theoretical hydrostatic load. • Only shorter wave periods break and form bores; longer tsunami-length waves do not break. • Tsunami overtopping volume is related to the duration of positive head over the crest. • Tsunami overtopping applies a relatively small (against the hydrostatic load) additional horizontal force.

The Phenomenon of Loss of Energy Flux Density in Pneumatic and Electromagnetic Generators for EPAT Therapy

Shock wave therapy involves introducing an acoustic wave into the living organism, whose pro-healing effect promotes the decomposition of stones and calcareous deposits. To generate such a wave, devices converting electrical energy into shock wave energy are used. Two versions of radial wave generators dominate the market: pneumatic and electromagnetic. The quality of the generator components and the design solutions significantly affect the amount of shock wave energy received. In the literature, there is a belief that, unfortunately, due to design limitations, it is not possible to obtain the same portion of energy for increasingly higher frequencies of generating wave pulses. The current study presents the results of a series of experiments carried out on two test benches. Two types of the wave generator were tested: pneumatic and electromagnetic. The obtained results clearly show that the mentioned problem occurs in both types of shock wave generators, regardless of whether it is a pneumatic or electromagnetic solution. This study discusses, in detail, the principle of operation of each type of generator and proposes a hypothesis on the source of the phenomenon.

Investigation of aerosol droplets diameter generated in aerosol jet printing

Abstract Aerosol jet printing is a contactless direct-write technique that could be used for the deposition of a variety of materials. First, used for electric paths, the technology was explored for many applications. The substantial part of the process is the generation of aerosols. The size of the droplets and the stability of the process affect the quality of the sprayed lines. This article investigates the diameter of the sprayed droplets, allowing future comparison of the results with sprayed lines. Droplets from ultrasonic and pneumatic generators were sprayed at their outlet on the polyethylene terephthalate (PET) foil. Using a digital microscope and the built-in algorithm, the diameter of the droplets was measured, and the dataset was collected as CSV files and served as a background to the box plot. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) scans were applied to verify the results obtained. The ink parameters used in the process have an influence on the aerosol generation and droplet diameter, whereas the carrier gas pressure has an impact mostly on the droplet diameter. In this case, the aerosol was produced from three types of ink in combination with two generators. For inks with a dynamic viscosity below 6.5 m·Pa−1·s−1 a stable range of 5–10 μm droplet diameter was observed. A high-viscosity ink (7.5–10.5 m·Pa−1·s−1) produced droplets with diameter in the range of 6–25 μm. The diameter of the droplet decreased from 7–22 μm to 1–5 μm with a reduction in the dynamic viscosity from 7.5–10.5 m·Pa−1·s−1 to 4.5–5.5 m·Pa−1·s−1.

Development of a Simulator Capable of Generating Age-Specific Pulse Pressure Waveforms for Medical Palpation Training

With the emergence of the metaverse and other human–computer interaction technologies, promising applications such as medical palpation training are growing for training and education purposes. Thus, the overarching goal of this study is to develop a portable and simple pulse pressure simulator that can reproduce age-specific pulse pressure waveforms for medical palpation training. For training applications, the simulator is required to produce accurate radial pulse waveforms consistently and repeatedly. To this end, exploiting the cam-based pneumatic pulse generation mechanism, this study intends to develop a cylindrical (or 3D) cam whose continually varying surface contains a wide range of age-related pulse pressure profiles. To evaluate the performance of the simulator, the reproduced pulse waveforms were compared with approximate radial pulse pressure waveforms based on in vivo data in terms of the augmentation index (AI) and L2 error. The results show that the errors were less than 10% for all ages, indicating that the proposed pulse simulator can reproduce the age-specific pulse waveforms equivalent to human radial pulse waveforms. The findings in this study suggest that the pulse simulator would be an excellent system for RAPP palpation training as it can reproduce a desired pulse accurately and consistently.

Erosion characteristics of molten aluminum droplets bouncing off solid walls in solid rocket motors

Based on the microscopic process of particles eroding the solid wall in the combustion chamber of solid rocket motors, the erosion mechanism of aluminum droplets in the process of vertical impact on solid walls is analyzed. Firstly, a method for measuring the impact force of the high-temperature molten-metal droplet is proposed on the basis of the pneumatic droplet generation method and piezoelectric force measurement technology. Then, the impact force of aluminum droplets with varing diameters and velocities is systematically studied. Additionally, the time-domain process of impact force in the rebound process of the aluminum droplets is obtained, and the coupling mechanism between the impact force and deformation process is analyzed and obtained. Then, based on the VOF interface tracking and the PLIC reconstruction method, the numerical model of the aluminum droplet impact force is established. On this basis, direct numerical simulations on the erosion effect of aluminum droplets on solid walls are carried out. Combining with the experimental results, the generation mechanism of the impact force and the influence mechanism of various parameters on the impact force during the rebound process of aluminum droplets are explored in depth. Ultimately, a semi-empirical prediction formula for the maximum value and duration of the impact force in the rebound process of the aluminum droplets is developed. Our research work can improve the cognition of the mechanism of the insulation materials in the combustion chamber of solid rocket motors, and thus expand the knowledge of engine structure design work.

Impulse Air Jet Action on the Convective Heat Exchange Tubular Surfaces in Boilers

Calculation and experimental investigations were carried out to determine the parameters of the impulse air jet created by the pneumatic generator of the air-impact system of the cleaning of tubular heat exchangers in boilers. Two configurations (lengthwise and checkerboard) of the arrangement of tubular heat exchangers located at distances from 1.0 m to 2.5 m of nozzle exit were experimentally investigated and the forces acting on them were determined. Numerical modeling of the impulse jet impact on heat exchange tubes was carried out. It was shown that an increase in the pressure of the generated impulse jet to 2.35 MPa makes it possible to significantly increase the acting force from 78 N to 1881 N at a large distance from the exhaust nozzle. The results obtained can be used in the development of specific systems for air impact cleaning systems of boiler units with other sizes and configurations of the heat exchange tubes.

Experimental Research on the Forward and Reverse Rotation Characteristics of a Pneumatic Motor for a Microscale Compressed Air Energy Storage System

Microscale compressed air energy storage is not dependent on geographical environment, exhibits a flexible layout, and is especially suitable for distributed energy systems. Herein, a test bench of microscale compressed air energy storage is established. The effects of key parameters, such as regulated pressure, current, voltage, and rotating speed, on the output performance of a pneumatic motor (PM) and generator are examined. The power performance, economic performance, and energy efficiency of the PM in forward and reverse rotations are also investigated. The differences in the output performances of the PM and generator under the forward and reverse rotations of the PM are analyzed. Experimental results show that the PM's power performance, economy, and efficiency in forward rotation are greater than those in reverse rotation. The power output of the generator with the PM in forward rotation is greater than that in reverse rotation. The maximum values of the power output and efficiency and the minimum compressed air consumption rate of the PM are 650 W, 6.92%, and 0.165 g J−1, respectively. The maximum efficiency of the generator is 94.35%.

A Pneumatic Generator Based on Gas-Liquid Reversible Transition for Soft Robots

The soft robots actuated by pressure, cables, thermal, electrosorption, combustion and smart materials are usually faced with the problems of poor portability, noise, weak load capacity, small deformation and high driving voltages. In this paper, a novel pneumatic generator for soft robots based on the gas-liquid reversible transition is proposed, which has the advantages of large output force, easy deformation, strong load capacity and high flexibility. The pressure of the pneumatic generator surges or drops flexibly through the reversible transformation between liquid and gas phase, making the soft actuator stretch or contract regularly, without external motors, compressors and pressure-regulating components. The gas-liquid reversible-transition actuation process is modeled to analyze its working mechanism and characteristics. The pressure during the pressurization stage increases linearly with a rate regulated by the heating power and gas volume. It decreases exponentially with the exponential term as a quadratic function of time at the fast depressurization stage, while with the exponential term as a linear function of time at the slow depressurization stage. The drop rate can be adjusted by changing the gas volume and cooling conditions. Furthermore, effectiveness has been verified through experiments of the prototype. The pressure reaches 25 bar with a rising rate of +3.935 bar/s when 5 mL weak electrolyte solution is heated at 800 W, and the maximum depressurization rate in air cooling is –3.796 bar/s. The soft finger actuated by the pneumatic generator can bend with an angular displacement of 67.5°. The proposed pneumatic generator shows great potential to be used for the structure, driving and sensing integration of artificial muscles.

High‐speed plasma treatment of polyethylene terephthalate films using ultrasound assisted dielectric barrier discharge

AbstractPolyethylene‐terephthalate (PET) films were treated using an air‐to‐air type atmospheric pressure dielectric barrier discharge (DBD) plasma in helium with ultrasonic irradiation, particularly for aiming at improving wettability. Airborne ultrasound was irradiated to the plasma using a pneumo‐acoustic stem‐jet Hartmann's generator. The wettability was significantly improved even when the treatment speed was up to 300 mm/s, corresponding to an estimated exposure time of approximately 30 ms. It is at least a factor of 30 shorter than the time required to achieve the same level of plasma treatment effect without ultrasonic irradiation. This effect opens an opportunity for industrial implementation of high‐speed plasma treatment of PET flexible packaging films by a straightforward embedding of pneumatic generators of ultrasound into existing wide‐web roll‐to‐roll commercial machines based on DBD.

Current Status of Liquid Metal Printing

This review focuses on the current state of the art in liquid metal additive manufacturing (AM), an emerging and growing family of related printing technologies used to fabricate near-net shape or fully free-standing metal objects. The various printing modes and droplet generation techniques as applied to liquid metals are discussed. Two different printing modes, continuous and drop-on-demand (DOD), exist for liquid metal printing and are based on commercial inkjet printing technology. Several techniques are in various stages of development from laboratory testing, prototyping, to full commercialization. Printing techniques include metal droplet generation by piezoelectric actuation or impact-driven, electrostatic, pneumatic, electrohydrodynamic (EHD), magnetohydrodynamic (MHD) ejection, or droplet generation by application of a high-power laser. The impetus for development of liquid metal printing was the precise, and often small scale, jetting of solder alloys for microelectronics applications. The fabrication of higher-melting-point metals and alloys and the printing of free-standing metal objects has provided further motivation for the research and development of liquid metal printing.

Some considerations for designing a pneumatic micro-droplet generator

Micro-droplet ejection is a liquid dispensing technology that has potential applications in many fields. Specifically, pneumatic ejection is actuated by a solenoid valve, which is set to ‘conduction’ state for a brief period of time Δt. High pressure gas of P 0 enters the liquid reservoir, then releases through a venting tube, creating a oscillating pressure waveform P(t), forcing the liquid out through a tiny nozzle to form a micro-droplet. For each actuation, P(t) is acquired by a high-speed pressure sensor, and the ejection state is obtained by high-speed photography and image processing methods. Some issues for the design of pneumatic micro-droplet ejector are discussed. For simulation of P(t), it is proposed within an electro-acoustic analogy picture that the acoustic resistance of the venting tube is mainly due to viscous effect and may vary with time during the whole ejection process. Based on this assumption, the calculated P(t) is more consistent with the actual measurement. Experimentally, the droplet ejection process for different length of venting tube is studied. With P 0 and Δt set, by increasing the venting tube length L, both the peak value P MAX1 and duration of the first positive pressure period increase, and more droplets are ejected from a single actuation. By setting different P 0, P MAX1 for different L is tuned to an identical and appropriate value, so that single droplet is ejected due to the first positive pressure period. However, with the increase of L, the peak value of the second positive pressure period P MAX2 increases. There is a certain probability that another droplet is ejected. It is realized that the increase of L can reduce gas consumption, but the multiple ejection is a drawback that should be considered in the design of pneumatic ejection system.

Mathematical modeling of theim pulse bubbling process of bulk mass by the coolant flow

The main directions of pneumodynamic system usage for storage of bulk agricultural products are bubbling and pneumatic mixing; loading and unloading of technological masses. During pneumodynamic impulse wave formation with alternation of supersonic and subsonic zones, which are limited by shock waves, sound force increasing on the technological mediumabout 150…170 dB, pressure increasing on the product mass due to compression-stretching at the pulse limits to amplitudes of 6…15 barare caused, that promotes implementation of loosening processes during the grain material storage. The developed scheme of the studied process involves the opposite arrangement of pneumatic impulse generators, which allows the formation of a stationary wave, that spreads the pulse energy in both longitudinal and transverse directions, covering the maximum space of the free flowing technological medium. Using the method of D’Alembert for solving the equations, methods of mathematical analysis and their processing in the MathCAD mathematical environment graphical and analytical dependences of force parameters of oscillatory system have been obtained. Choosing an effective mode of pneumodynamic loosening, the force pulse magnitude and the regularities of its change under conditions of the highest mechanical resistance of the free-flow mass have been used as the evaluation criteria the standing wave energy.

Experimental Studies on the Reactive Thrust of the Mobile Robot of Arbitrary Orientation

The problem of creating mobile robots of arbitrary orientation in the technological space is to ensure reliable retention of robots on the surface of any orientation. Therefore, well-known experimental studies are mainly devoted to the creation of systems for coupling the robot to the surface along which it moves. The purpose of this study is to create a device for compensating the gravitational load of a mobile robot. The article contains the results of experimental testing of a fundamentally new approach to counteract the gravitational load of a mobile robot, namely, the expediency of equipping the robot with a source of reactive thrust of a non-chemical origin. A pneumatic generator of aerodynamic lift is proposed as such a source. Such a force partially compensates or completely overcomes the gravitational load, while not allowing the transformation of a mobile robot into an aircraft. The specified condition is necessary to perform contact power technological operations in the maintenance of various industrial facilities. In other words, the thrust force should not exceed the adhesion forces of the mobile robot to the displacement surface. As a research method, a full factorial experiment of the operation of a jet thrust generator was used, which is a new way to increase the reliability of holding the robot on an arbitrary surface. The article describes the methodology and description of the full factorial experiment with varying independent factors at two extreme levels. As a result, an experimental solution to the problem of finding the quasi-optimal values of the aerodynamic lifting force depending on the parameters of the jet thrust generator is obtained. As a result, the combination of a new robot design with the results of experimental studies confirms the feasibility of using a pneumatic jet thrust generator as a means of increasing the reliability of holding mobile robots on an arbitrary orientation surface in the technological space.

Experimental Studies on the Reactive Thrust of the Mobile Robot of Arbitrary Orientation

The problem of creating mobile robots of arbitrary orientation in the technological space is to ensure reliable retention of robots on the surface of any orientation. Therefore, well-known experimental studies are mainly devoted to the creation of systems for coupling the robot to the surface along which it moves. The purpose of this study is to create a device for compensating the gravitational load of a mobile robot. The article contains the results of experimental testing of a fundamentally new approach to counteract the gravitational load of a mobile robot, namely, the expediency of equipping the robot with a source of reactive thrust of a non-chemical origin. A pneumatic generator of aerodynamic lift is proposed as such a source. Such a force partially compensates or completely overcomes the gravitational load, while not allowing the transformation of a mobile robot into an aircraft. The specified condition is necessary to perform contact power technological operations in the maintenance of various industrial facilities. In other words, the thrust force should not exceed the adhesion forces of the mobile robot to the displacement surface. As a research method, a full factorial experiment of the operation of a jet thrust generator was used, which is a new way to increase the reliability of holding the robot on an arbitrary surface. The article describes the methodology and description of the full factorial experiment with varying independent factors at two extreme levels. As a result, an experimental solution to the problem of finding the quasi-optimal values of the aerodynamic lifting force depending on the parameters of the jet thrust generator is obtained. As a result, the combination of a new robot design with the results of experimental studies confirms the feasibility of using a pneumatic jet thrust generator as a means of increasing the reliability of holding mobile robots on an arbitrary orientation surface in the technological space.

Ejection state prediction for a pneumatic micro-droplet generator by BP neural networks

Ejection state prediction for a pneumatic micro-droplet generator by BP neural networks

321 Comparison of Low Intensity Shockwave for Erectile Dysfunction Using Electrohydraulic vs Radial Shockwave Generators

Low intensity shockwave therapy (LSWT) has emerged as a novel treatment of arteriogenic erectile dysfunction (ED). Part of the difficulty of comparing results in the literature is the use of multiple different machines and protocols. Even controlling for total energy applied, the shape of the waveform depending on the shock generator is different and might produce variable biologic effects. To compare outcomes of LSWT for men with ED between devices that generate either electrohydrolic spark waves or radial waves. A retrospective chart review compiled the outcomes of men who had LSWT for ED either using the TRT Urogold 100 (electrohydrolic generation) or the Zimmer enpuls (pneumatic radial generation). All men received 6 weekly treatments. On the Urogold 100, we used a total of 3000 shocks at 0.09 mJ/mm2 and for the Zimmer we used 10,000 shocks at 15 Hz and 90 mJ energy (both are standard protocols for each respective device). There were 6 treatment sites: one at each crus of the penis and 2 on the shaft bilaterally. SHIM score assessed erectile function before and 6 weeks after therapy. Men also self reported erectile hardness on a scale of 0 (no change), 1 (firm enough for penetration) or 2 (completely firm). Data was compared with paired or unpaired t test, Chi squared or Kruskal-Wallis as appropriate and significance set at p<0.05.

Seismic and Seismochemical Stimulation Increases Well Injectivity and Productivity

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 190456, “Increasing Well Injectivity and Productivity by Seismic and Seismochemical Stimulation,” by K. Furman, S. Miftakhov, SPE, M. Nazyrov, R. Nefedov, and V. Zamakhaev, Terratec, and A. Andrianov, AIA Consulting, prepared for the 2018 SPE EOR Conference at Oil and Gas West Asia, Muscat, Oman, 26–28 March. The paper has not been peer reviewed. Many oil fields in Russia and the Commonwealth of Independent States are in late-development stages, with waterflooding having being used for decades. A relatively new technology in production optimization is wave stimulation, in which the wellbore and reservoir are treated by acoustic, seismic, or other types of waves generated by tools. Approximately 250 wells have been treated in this manner, with a high success rate and significant oil-production increase. This paper discusses the potential of seismic and seismochemical well simulation in particular within the scope of this recent technology. Introduction Wave-stimulation technologies have short treatment times and can be applied in different types of formations and wells. This paper focuses on seismic-impact well treatment. The well treatment is based on a wellhead pneumatic generator that uses special valves. Energy is generated at the surface with compressed inert gas and released into the well. A shock wave then propagates through the liquid-filled well column and transforms into a seismic wave in situ. Movement of the shock wave creates a damped self-oscillating process with a frequency of 0.2 Hz, the effect of which can stimulate injection and production wells. One method of increasing the efficiency of seismic stimulation is use in conjunction with the injection of chemical reagents. Mechanisms of Seismic and Seismochemical Stimulation No generally accepted theory describes the effects of seismic impact on reservoirs. On the basis of theoretical, experimental, and field research, various authors have proposed mechanisms and concepts, which are described in the complete paper. Porosity and Permeability Change in Dilatancy Area for Sandstones. Studies of dilatancy processes under dynamic effects have shown that, for sufficiently high unevenness of the stressed state, dilatancy processes occur even at stresses that are only 3–5% of the ultimate strength, causing irreversible change in the rock density, porosity, strength, and permeability. Dilatancy is observed in the deformation of soils and rocks. Extensive experimental data on the deformation of a wide class of formations under volumetric stressed-state conditions show that compaction is seen in highly porous rocks, while loosening is seen in dense rocks. Reduction in the volume of highly porous rocks occurs as the result of a reduction in the number of defects. Positive (compaction) and negative (loosening) rock-dilatancy values are related to the value of the initial effective porosity. If the effective porosity value is less than a certain limiting value, then the rock is dense and loosens during deformation. When the effective porosity is greater than its limiting value, the rock is compacted. However, the compaction of the rock can occur up to a certain value, after which it breaks down. The main influence on the amount of dilatancy is the result of an uneven load (i.e., the ratio of the minimum main stress to the maximum). However, at the same level and at the magnitude of the uneven loading in the stronger rocks, the dilatant component of the volume deformation exceeds the rock compaction more than is seen in less-rigid rocks.