Performances of a Stinger PDC cutter breaking granite: Cutting force and mechanical specific energy in single cutter tests

The Stinger PDC cutter has high rock-breaking efficiency and excellent impact and wear resistance, which can significantly increase the rate of penetration (ROP) and extend PDC bit life for drilling hard and abrasive formation. The knowledge of force response and mechanical specific energy (MSE) for the Stinger PDC cutter is of great importance for improving the cutter's performance and optimizing the hybrid PDC bit design. In this paper, 87 single cutter tests were conducted on the granite. A new method for precisely obtaining the rock broken volume was proposed. The influences of cutting depth, cutting angle, and cutting speed on cutting force and MSE were analyzed. Besides, a phenomenological cutting force model of the Stinger PDC cutter was established by regression of experimental data. Moreover, the surface topography and fracture morphology of the cutting groove and large size cuttings were measured by a 3D profilometer and a scanning electron microscope (SEM). Finally, the rock-breaking mechanism of the Stinger PDC cutter was illustrated. The results indicated that the cutting depth has the greatest influence on the cutting force and MSE, while the cutting speed has no obvious effects, especially at low cutting speeds. As the increase of cutting depth, the cutting force increases linearly, and MSE reduces with a quadratic polynomial relationship. When the cutting angle raises from 10° to 30°, the cutting force increases linearly, and the MSE firstly decreases and then increases. The optimal cutting angle for breaking rock is approximately 20°. The Stinger PDC cutter breaks granite mainly by high concentrated point loading and tensile failure, which can observably improve the rock breaking efficiency. The key findings of this work will help to reveal the rock-breaking mechanisms and optimize the cutter arrangement for the Stinger PDC cutter.

Comparative Study of the Rock-breaking Mechanism of a Disc Cutter and Wedge Tooth Cutter by Discrete Element Modelling

The operation of a shield tunnel boring machine(TBM)in a high-strength hard rock stratum results in significant cutter damage,adversely affecting the thrust and torque of the cutter head.Therefore,it is very important to carry out the research on the stress characteristics and optimize the cutter parameters of cutters break high-strength hard rock.In this paper,the rock-breaking performance of cutters in an andesite stratum in the tunnel of Qingdao Metro Line No.8 was investigated using the discrete element method and theoretical analysis.The rock-breaking processes of a disc cutter and wedge tooth cutter were simulated by software particle flow code PFC^(3D),and the rock-breaking degree,stress of the cutter,and rock-breaking specific energy were analyzed.The rock damage caused by the cutter in a specific section was divided into three stages:the advanced influence,crushing,and stabilizing stages.The rock-breaking degree and the tangential and normal forces of the wedge tooth cutter are larger than that of the disc cutter under the same conditions.The disc cutter(wedge tooth cutter)has the highest rock-breaking efficiency at a cutter spacing of 100 mm(110 mm)and a penetration depth of 8 mm(10 mm),and the rock-breaking specific energy is 11.48 MJ/m^(3)(12.05 MJ/m^(3)).Therefore,two types of cutters with different penetration depths or cutter spacing should be considered.The number of teeth of wedge tooth cutters can be increased in hard strata to improve the rock-breaking efficiency of the shield.The research results provide a reference for shield cutterhead selection and cutter layout in similar projects.

THEORETICAL CALCULATION OF SPECIFIC INTERFACIALENERGY OF SEMICOHERENT INTERFACE BETWEEN MICROALLOY CARBONITRIDES AND AUSTENITE

According to the misfitting dislocation theory,a method of theoretical calculation was devel- oped for the specific energy of the semicoherent interface between microalloy carbonitrides and austenite matrix.The calculating formulae were derived and the results were satisfactorily applied on the research works.

Specific energy optimization in sawing of rocks using Taguchi approach

This work aims at selecting optimal operating variables to obtain the minimum specific energy(SE) in sawing of rocks.A particular granite was sampled and sawn by a fully automated circular diamond sawblades.The peripheral speed,the traverse speed,the cut depth and the flow rate of cooling fluid were selected as the operating variables.Taguchi approach was adopted as a statistical design of experimental technique for optimization studies.The results were evaluated based on the analysis of variance and signal-to-noise ratio(S/N ratio).Statistically significant operating variables and their percentage contribution to the process were also determined.Additionally,a statistical model was developed to demonstrate the relationship between SE and operating variables using regression analysis and the model was then verified.It was found that the optimal combination of operating variables for minimum SE is the peripheral speed of 25 m/s,the traverse speed of 70 cm/min,the cut depth of 2 cm and the flow rate of cooling fluid of 100 mL/s.The cut depth and traverse speed were statistically determined as the significant operating variables affecting the SE,respectively.Furthermore,the regression model results reveal that the predictive model has a high applicability for practical applications.

Prediction Model for Net Cutting Specific Energy in CNC Turning

A prediction model for net cutting specific energy in computer numerical control(CNC)turning based on turning parameters and tool wear is developed.The model can predict the net cutting energy consumption before turning.The prediction accuracy of the model is verified in AISI 1045 steel turning.The comparative experimental results show that the prediction accuracy of the model is significantly improved because the influence of tool wear is taken into account.Finally,the influences of turning parameters and tool wear on net cutting specific energy are studied.With the increase of cutting depth,the net cutting specific energy decreases.With the increase of spindle speed,the additional load loss power of spindle drive system increases,so the net cutting specific energy increases.The net cutting specific energy increases approximately linearly with tool wear.The results are helpful to formulate efficient and energy-saving CNC turning schemes and realize low‑carbon manufacturing.

Theoretical Prediction of Negative Energy Specific to the Electron

If an electron emits all of its rest mass energy mec2, the relativistic energy of the electron will become zero. According to the special theory of relativity, an electron whose relativistic energy is zero does not have photon energy. In this paper, however, an electron is regarded as having photon energy mec2 and negative energy −mec2, even when its relativistic energy is zero. The state where relativistic energy is zero is achieved due to the positive energy and negative energy canceling each other out. Relativistic energy becomes zero for an electron in a hydrogen atom when the principle quantum number n is zero. The author has already pointed out the existence of an energy level with n=0. If this model is used, it is possible for an electron in the state with n=0 to emit additional photons, and transition to negative energy levels. The existence of negative energy specific to the electron has previously been nothing more than a conjecture. However, this paper aims to theoretically show the existence of negative energy based on a discussion using an ellipse. The results show that the electron has latent negative energy.

Optimization of Drilling Parameters by Analysis of Formation Strength Properties with Utilization of Mechanical Specific Energy

By increasing the daily needs of human energy, human manipulation of natural energy sources is expanded and encouraged the human society to developing science, knowledge and technology. Mechanical specific energy required energy for drilling the unit of formation volume. This parameter can be used for functional analysis of drilling, drilling bit optimization and investigating of instability has been made during drilling operations. This parameter can be used for decreasing of drilling costs by increasing drilling speed, optimized the useful life of the drilling bit and determine the right time to replace the drilling bit, and in some cases reduced to a minimum amount. In South Pars field in Iran, many wells have been drilled;however detailed statistics processes hadn’t done for optimizing drilling parameters and their impact on mechanical specific energy. By results of these studies, we can analyze performance and drilling parameters such as weight on drilling bit, rotational speed, penetration rate, etc. In the most investigated cases, mechanical specific energy at the final period time of drilling on each wells has been increased gradually due to the speed movement reduction. Although by investigating middle formations in section of 12.25 inch, all existing wells on a platform in one of the phases of Iran’s South Pars field are being studied, which contains formations such as Hith, Surmeh, Neyriz, Dashtak and Kangan. Studies were done in two parts. In the first part, the range of optimized drilling parameters that is increasing drilling speed and reducing the required amount of energy for drilling formation. This process by investigating mechanical specific energy and its relationship with uniaxial compressive strength in five studied formation have been presented. In the second part, correlations to predict the mechanical specific energy in this area by statistical methods by SPSS software, presented and reviewed. Then, by the most appropriate relationship, the most influential drilling parameters on mechanical specific energy have been set. However, for drilling the next wells in this area drilling parameters with the most priority influences on mechanical specific energy, proposed in the optimum range, will be recommended.

Energy dissipation mechanism and ballistic characteristic optimization in foam sandwich panels against spherical projectile impact

This study systematically examines the energy dissipation mechanisms and ballistic characteristics of foam sandwich panels(FSP)under high-velocity impact using the explicit non-linear finite element method.Based on the geometric topology of the FSP system,three FSP configurations with the same areal density are derived,namely multi-layer,gradient core and asymmetric face sheet,and three key structural parameters are identified:core thickness(t_(c)),face sheet thickness(t_(f))and overlap face/core number(n_(o)).The ballistic performance of the FSP system is comprehensively evaluated in terms of the ballistic limit velocity(BLV),deformation modes,energy dissipation mechanism,and specific penetration energy(SPE).The results show that the FSP system exhibits a significant configuration dependence,whose ballistic performance ranking is:asymmetric face sheet>gradient core>multi-layer.The mass distribution of the top and bottom face sheets plays a critical role in the ballistic resistance of the FSP system.Both BLV and SPE increase with tf,while the raising tcor noleads to an increase in BLV but a decrease in SPE.Further,a face-core synchronous enhancement mechanism is discovered by the energy dissipation analysis,based on which the ballistic optimization procedure is also conducted and a design chart is established.This study shed light on the anti-penetration mechanism of the FSP system and might provide a theoretical basis for its engineering application.

Research Progress on High Specific Energy Cathode Materials for Rechargeable Lithium Sulfur Batteries

An overview of the developing survey, research actuality and the future development of high specific energy and power lithium sulfur rechargeable batteries was presented systemically. By introducing the character of sulfur composite material and discussing some promising cathode materials, it may provide some foundation for people to go deep into researching and empoldering the sulfur composite material.

Derivation of Specific Velocity of Body Moving under Gravity with Zero Total Energy

Mathematical solutions predict abstract conditions that indicate limits or bounds for physical processes. Generally, experimental verifications and physical observations on physical processes validate the mathematical predictions. Sometimes these predictions lead to new theories and concepts that form basis of better understanding of the natural processes. Gravitational interactions between bodies are natural physical processes. A smaller body moves under the influence of gravity, due to the gravitational effect of another large body. Newton’s classical gravitational theory addresses the interactions at low velocities. Einstein’s general relativity provides firm basis for gravitational interactions. Observations over past 100 years prove the mathematical precision and predictions of general relativity. Einstein’s special relativity forms the foundation of quantum physics. In this paper, the author applies concepts of special relativity to classical two body Newtonian gravitational problem. The study predicts a new mathematically viable condition that when a body moves at a specific velocity derived in this paper, the total energy of the moving body is zero. The specific velocity is a constant. At velocities far less than specific velocity, the total energy is negative and is equal to classical value of half the potential energy. At velocities, greater the specific velocity the total energy is positive. The specific velocity condition also enables determination of specific mass of gravitating body, as well as the specific distance of the moving body from gravitating body, at which the total energy of moving body is zero.

Effects of Transverse Field on Internal Energy and Specific Heat of a Molecular-Based Materials

The molecular-based magnetic materials AFe11 Fe111（C2O4）3 have a honeycomb structure in which FeII （S = 2） and FeIH （S= 5/2） occupy sites alternately. They can be described as mixed spin-2 and spin-5/2 Ising model with ferrimagnetic interlayer coupling. The influences of the transverse field on the internal energy and the specific heat of the molecalar-based magnetic system have been studied numerically by using the effective-field theory with self-spin correlations and the differential operator technique.

Internal energy and specific antiferromagnetic heat in a ferromagnetic- double layers

The internal energy and specific heat of a Heisenberg ferro- antiferromagnetic double-layer system are studied by using spin-wave theory and the retarded Green function method at low temperatures. Numerical results show that the antiferromagnetic intralayer coupling J2 has an important influence on internal energy and specific heat for a four-sublattice system with antiferromagnetic （or ferrimagnetic） interlayer couplings.

Dispersion and Polar Component of Specific Surface Free Energy of NaCl(100), KCl(100), and KBr(100) Single Crystal Surfaces

Contact angle of ethylene glycol and formamide on (100) faces of NaCl, KCl, and KBr single crystal was measured, and the specific surface free energy (SSFE) was calculated. Dispersion component of the SSFE was 90.57, 93.78, and 99.52 mN&#183m-1 for NaCl, KCl, and KBr, respectively. Polar component of the SSFE was 1.05, 0.65, and 0.45 mN&#183m-1 for NaCl, KCl, and KBr. Such a large ratio of dispersion component of SSFE results from the neutrality of the crystal surface of alkali halide. Lattice component of alkali halide is 780, 717 and 689 kJ&#183mol-1 for NaCl, KCl, and KBr. The larger lattice enthalpy decreases dispersion component, and increases polar component of the SSFE. The larger lattice enthalpy is considered to enhance the rumpling of the crystal surface more strongly, and such rumpling is considered to decrease the neutrality of the crystal surface.

Evaluation of Patient-Specific Quality Assurance for Carbon Ion Radiotherapy Using Full Energy Scanning Method at QST Hospital

Purpose: Patient-specific QA (PSQA) measurements for carbon ion radiotherapy (CIRT) are critical components of processes designed to identify discrepancies between calculated and delivered doses. We report the results of PSQA conducted at the QST Hospital during the period from September 2017 to March 2018. Methods: We analyzed PSQA results for 1448 fields for 10 disease sites with various target volumes, target depths and number of energy layers. For the PSQA, all the planned beams were recalculated on a water phantom with treatment planning software. The recalculated dose distributions were compared with the measured distributions using a 2D ionization chamber array at three depths, including 95% of the area of the prescription dose. These recalculated dose distributions were evaluated using the 3%/3mm gamma index with a passing threshold of 90%. Results: The passing rates for prostate, head and neck, and bone and soft tissue were 96.8%, 99.3%, and 91.7%, respectively. Additionally, 94.7% of lung plans with low energy beams passed. Overall, the CIRT in the QST Hospital reached a high passing rate of more than 95%. Although the remaining 5% failed to pass, there was no dependence between measurement depth and disease sites in these failures. Conclusion: Using PSQA measurements, we confirmed consistency between the planned and delivered doses for CIRT using the full energy scanning method.

Dominant role of wettability in improving the specific capacitance

Here we report a strategy to enhance the energy density of supercapacitors by increasing the utilization rate of the specific surface area(SSA)via wettability improvement. The nonporous gold(NPG) film is used as the electrodes and the ionic liquid [EMIM]BF4 is the electrolyte. When the electrode is coated by paraffin, an increase of the contact angle leads to a remarkable reduction of the specific capacitance. While when acetonitrile is added into the electrolyte, the contact angle is decreased and the utilization rate of SSA is improved, which results in an increase of the specific capacitance. The addition of isopropyl acetate into the electrolyte leads to a further increase of the specific capacitance. To generalize the role of the wettability in improving the energy density, a carbon-based electrode is evaluated in the solution of potassium hydroxide. An addition of propyl alcohol into the potassium hydroxide solution leads to an increase of the specific capacitance, as well as a long-term stability of the supercapacitor. The role of conductivity in this study is excluded by designing experiments. This paper highlights the significance of wettability in determining the specific capacitance, showing an alternative to improve the energy density of supercapacitors.

Specific-Scene Oriented Pedestrian Detection in Visual Sensor Network

Pedestrian detection is one of the most important problems in the visual sensor network. Considering that the visual sensors have limited cap ability, we propose a pedestrian detection method with low energy consumption. Our method contains two parts: one is an Enhanced Self-Organizing Background Subtraction (ESOBS) based foreground segmentation module to obtain active areas in the observed region from the visual sensors; the other is an appearance model based detection module to detect the pedestrians from the foreground areas. Moreover, we create our own large pedestrian dataset according to the specific scene in the visual sensor network. Numerous experiments are conducted in both indoor and outdoor specific scenes. The experimental results show that our method is effective.

Meta-analysis of CO_(2) conversion,energy efficiency,and other performance data of plasma-catalysis reactors with the open access PIONEER database

This paper brings the comparison of performances of CO_(2)conversion by plasma and plasma-assisted catalysis based on the data collected from literature in this field,organised in an open access online database.This tool is open to all users to carry out their own analyses,but also to contributors who wish to add their data to the database in order to improve the relevance of the comparisons made,and ultimately to improve the efficiency of CO_(2)conversion by plasma-catalysis.The creation of this database and database user interface is motivated by the fact that plasma-catalysis is a fast-growing field for all CO_(2)conversion processes,be it methanation,dry reforming of methane,methanolisation,or others.As a result of this rapid increase,there is a need for a set of standard procedures to rigorously compare performances of different systems.However,this is currently not possible because the fundamental mechanisms of plasma-catalysis are still too poorly understood to define these standard procedures.Fortunately however,the accumulated data within the CO_(2)plasma-catalysis community has become large enough to warrant so-called“big data”studies more familiar in the fields of medicine and the social sciences.To enable comparisons between multiple data sets and make future research more effective,this work proposes the first database on CO_(2)conversion performances by plasma-catalysis open to the whole community.This database has been initiated in the framework of a H_(2)0_(2)0 European project and is called the“PIONEER Data Base”.The database gathers a large amount of CO_(2)conversion performance data such as conversion rate,energy efficiency,and selectivity for numerous plasma sources coupled with or without a catalyst.Each data set is associated with metadata describing the gas mixture,the plasma source,the nature of the catalyst,and the form of coupling with the plasma.Beyond the database itself,a data extraction tool with direct visualisation features or advanced filtering functionalities has been developed and is available online to the public.The simple and fast visualisation of the state of the art puts new results into context,identifies literal gaps in data,and consequently points towards promising research routes.More advanced data extraction illustrates the impact that the database can have in the understanding of plasma-catalyst coupling.Lessons learned from the review of a large amount of literature during the setup of the database lead to best practice advice to increase comparability between future CO_(2)plasma-catalytic studies.Finally,the community is strongly encouraged to contribute to the database not only to increase the visibility of their data but also the relevance of the comparisons allowed by this tool.

Stability in Liquid Phases of Molecular Compounds Composed of Saturated Atoms: Application with the Even-Odd Rule and a Specific Periodic Table for Liquids

Building on the idea that molecules in liquid phase associate into multi-molecular complexes through covalent bonds, the present article focuses on the possible structures of these complexes. Saturation at atomic level is a key concept to understand where connections occur and how far molecules aggregate. A periodic table for liquids with saturation levels is proposed, in agreement with the even-odd rule, for both organic and inorganic elements. With the aim at reaching the most stable complexes, meaning no other chemical reactions can occur in the liquid phase, the structure of complexes resulting from liquefaction of about 30 molecules is devised. The article concludes that complexes in liquids generally assume rounded shapes of an intermediate size between gas and solid structures. It shows that saturation and covalent bonds alone can explain the specific properties of liquids. While it is generally acknowledged that molecular energy in gases and solids are respectively linear kinetic and vibratory, we suggest that rotatory energy dominates in liquids.

On Energy Assessment of Titanium Alloys Belt Grinding Involving Abrasive Wear Effects

Improved energy utilisation,precision,and quality are critical in the current trend of low-carbon green manufactur-ing.In this study,three abrasive belts were prepared at various wear stages and characterised quantitatively.The effects of abrasive belt wear on the specific grinding energy partition were investigated by evaluating robotic belt grinding of titanium plates.A specific grinding energy model based on subdivided tangential forces of cutting and sliding was developed for investigating specific energy and energy utilisation coefficient EUC.The surface mor-phology and Abbott–Firestone curves of the belts were introduced to analyse the experimental findings from the per-spective of the micro cutting behaviour.The specific grinding energy increased with abrasive belt wear,especially when the belt was near the end of its life.Moreover,the belt wear could lead to a predominance change of sliding and chip formation energy.The highest EUC was observed in the middle of the belt life because of its retained sharp cutting edge and uniform distribution of the grit protrusion height.This study provides guidance for balancing the energy consumption and energy utilization efficiency of belt grinding.