Study on the coupling calculation method for the launch dynamics of a self-propelled artillery multibody system considering engraving process

The launch dynamics theory for multibody systems emerges as an innovative and efficacious approach for the study of launch dynamics,capable of addressing the challenges of complex modeling,diminished computational efficiency,and imprecise analyses of system dynamic responses found in the dynamics research of intricate multi-rigid-flexible body systems,such as self-propelled artillery.This advancement aims to enhance the firing accuracy and launch safety of self-propelled artillery.Recognizing the shortfall of overlooking the band engraving process in existing theories,this study introduces a novel coupling calculation methodology for the launch dynamics of a self-propelled artillery multibody system.This method leverages the ABAQUS subroutine interface VUAMP to compute the dynamic response of the projectile and barrel during the launch process of large-caliber self-propelled artillery.Additionally,it examines the changes in projectile resistance and band deformation in relation to projectile motion throughout the band engraving process.Comparative analysis of the computational outcomes with experimental data evidences that the proposed method offers a more precise depiction of the launch process of self-propelled artillery,thereby enhancing the accuracy of launch dynamics calculations for self-propelled artillery.

Application of Choquet Integral-Importance-Performance Analysis and TOPSIS Methods in Approaching the Preference Factors of Calligraphy and Seal Engraving Imagery

Classical Chinese characters,presented through calligraphy,seal engraving,or painting,can exhibit different aesthetics and essences of Chinese characters,making them the most important asset of the Chinese people.Calligraphy and seal engraving,as two closely related systems in traditional Chinese art,have developed through the ages.Due to changes in lifestyle and advancements in modern technology,their original functions of daily writing and verification have gradually diminished.Instead,they have increasingly played a significant role in commercial art.This study utilizes the Evaluation Grid Method(EGM)and the Analytic Hierarchy Process(AHP)to research the key preference factors in the application of calligraphy and seal engraving imagery.Different from the traditional 5-point equal interval semantic questionnaire,this study employs a non-equal interval semantic questionnaire with a golden ratio scale,distinguishing the importance ratio of adjacent semantic meanings and highlighting the weighted emphasis on visual aesthetics.Additionally,the study uses Importance-Performance Analysis(IPA)and Technique for Order Preference by Similarity to Ideal Solution(TOPSIS)to obtain the key preference sequence of calligraphy and seal engraving culture.Plus,the Choquet integral comprehensive evaluation is used as a reference for IPA comparison.It is hoped that this study can provide cultural imagery references and research methods,injecting further creativity into industrial design.

DXF File Identification with C# for CNC Engraving Machine System

This paper researches the main technology of open CNC engraving machine, the DXF identification technology. Agraphic information extraction method is proposed. By this method, the graphic information in DXF file can be identified and transformed into bottom motion controller’s code. So the engraving machine can achieve trajectory tracking. Then the open CNC engraving machine system is developed with C#. At last, the method is validated on a three axes motion experiment platform. The result shows that this method can efficiently identify the graphic information including line, circle, arc etc. in DXF file and the CNC engraving machine can be controlled well.

Rock Engravings and Paintings: Rethinking of the Cupules, Gongs, and Grinding Hollows of Siuyu and Ughaugha in Singida East (Tanzania)

Our recent archaeological expeditions in the Siuyu and Ughaugha wards of Singida eastern province have recuperated the very compelling rock engravings (petroglyphs) that weren’t reported in Tanzania before. Archaeologically, Singida’s fame emanated from her endowments of rock paintings. However;during this research, we did discover rock cupules, gongs, and grinding hollows art together with rock paintings (pictographs) that have opened up a new avenue for rock art studies in Tanzania. We carried out intensive site surveys around four sites namely Siuyu, Ngaghe, Misimbwa and Ughaugha B with the aims of solely examining, recording, and documenting archaeological artifacts on the surface in order to research the cultural and behavioural patterns of early humans in the Singida region. Surveys also enabled us to locate suitable areas where future excavations would be established. In some cases, ethnographic enquiries were employed to get supplementary information on the present-day use of rock art sites. Besides, we interviewed local people to assess their general understanding of the presence of more sites or helping in locating, and discovering new sites. Through ethnographic inquiries, we discovered several sites with substantial number of rock engravings that were never document by any researcher. On top of that, this study reports other archaeological potentials of the region by describing in detail their significances for future research undertakings. Additionally, this paper article reports on the occurrence of Middle Stone Age (MSA) archaeological assemblages from the open-air site and the presence of grinding hollows and rock cupules (Siuyu complexes) in central Tanzania for the first time.

Art of Chinese Seal Engraving Inscribed on the Representative List of the Intangible Cultural Heritage of Humanity in 2009

The art of seal en graving is a comerstone of Chinese fine arts. The seal was originally used as a signature or sign of authority, but it came to be used by all social classes and in much of Asia. The Seal *Engravers Society of Xiling in east China's Zhejiang Province, which was founded a century ago, preserves the art of seal engraving along with approximately 100 other specialized institutions. The design is first sketched on paper, and then engraved on stone, in reverse, with a knife.

Tribology of rotating band and gun barrel during engraving process under quasi-static and dynamic loading

The engraving process of a projectile rotating band is one of the most basic research aspects in interior ballistics,which has not been thoroughly understood thus far.An understanding of this process is of great importance from the viewpoints of optimal design,manufacturing,use,and maintenance of gun and projectile.In this paper,the interaction of copper and nylon rotating bands with a CrNiMo gun barrel during engraving was studied under quasi‐static and dynamic loading conditions.The quasi‐static engraving tests were performed on a CSS‐88500 electronic universal testing machine(EUTM)and a special gas‐gun‐based test rig was designed for dynamic impact engraving of the rotating bands.The mechanical behaviors of copper and nylon were investigated under strain rates of 10^(−3) s^(−1) and 2×10^(3) s^(−1) using an MTS 810 and a split Hopkinson pressure bar(SHPB),respectively.Morphologies of the worn surfaces and cross‐sectional microstructures were observed with scanning electron microscope(SEM)and optical microscope(OM).It was found that large deformation and severe friction occur during engraving.The surface layer is condensed and correlated with a hardness gradient along the depth from the top worn surface.The structure of the rotating band and gun bore,band material,and loading rate have great effects on band engraving.The flow stress‐strain of the copper strongly depends on the applied strain rate.It is suggested that strain rate and temperature play significant roles in the deformation mechanism of rotating bands.

Art of Engraving

Chinese artist Luo Pengpeng showcases her new works of seal engraving Ai n exhibition of Luo Pengpeng’s seal 1 engraving works, sponsored by the 1 Ministry of Culture of China and the All-China Women’s Federation, is being held

Calligraphy and Seal Engraving Exhibition at Sinitude Gallery

On April 9, 2010, an exhibition of the calligraphy and sealengraving works of Wang Yuzhong opened at Sinitude Galleryin the Chaoyang District of Beijing. Famous artists

Ancient Engravings Found in Somerset Cave

英国布利斯托尔大学两名学者最近在英国南部发现了一万年前的旧石器时代的窑洞艺术。这个发现令人激动,因为这个洞穴曾被视为英国历史上最古老的墓穴,时值冰川世纪末期,即中石器时代初期。通过对这个洞穴的考古,人们对于冰川世纪的建筑、雕刻等有了更进一步的认识。

Numerical simulation of the coupled dynamics model of the projectile engraving process

The projectile engraving process directly influences the projectile motion in-bore and impacts the firing accuracy,firing safety,and barrel life of the gun.For this reason,attention has been focused on this research topic.To address the limitations of the“instantaneous engraving”hypothesis adopted in the classical interior ballistic theory,the VUAMP user subroutine,one of ABAQUS's secondary development interfaces,is utilized in this paper to realize the modeling and numerical simulation of a coupled dynamics model of the projectile engraving process.In addition to facilitating engineering applications,a polynomial fitting formula of the engraving resistance obtained by simulation is proposed and then used as a supplement to establish a closed and solvable interior ballistic model considering the projectile engraving process.By comparing with test data,the simulation accuracy of the coupled dynamics model is verified.Simulation results reveal that the engraving process takes 3.8 ms,accounting for 26%of the whole launch process,which takes 14.6 ms,demonstrating that the process is not instantaneous.The results of this paper can serve as a reference for future studies on the coupled solution of the projectile engraving process and interior ballistics of guns or gun-like equipment.

Flexible Waterproof Piezoresistive Pressure Sensors with Wide Linear Working Range Based on Conductive Fabrics

Developing flexible sensors with high working performance holds intense interest for diverse applications in leveraging the Internet-of-things(IoT)infrastructures.For flexible piezoresistive sensors,traditionally most efforts are focused on tailoring the sensing materials to enhance the contact resistance variation for improving the sensitivity and working range,and it,however,remains challenging to simultaneously achieve flexible sensor with a linear working range over a high-pressure region(>100 kPa)and keep a reliable sensitivity.Herein,we devised a laserengraved silver-coated fabric as"soft"sensor electrode material to markedly advance the flexible sensor's linear working range to a level of 800 kPa with a high sensitivity of 6.4 kPa^-1 yet a fast response time of only 4 ms as well as long-time durability,which was rarely reported before.The integrated sensor successfully routed the wireless signal of pulse rate to the portable smartphone,further demonstrating its potential as a reliable electronic.Along with the rationally building the electrode instead of merely focusing on sensing materials capable of significantly improving the sensor's performance,we expect that this design concept and sensor system could potentially pave the way for developing more advanced wearable electronics in the future.

High-performance magnesium ion asymmetric Ppy@FeOOH//Mn3O4 micro-supercapacitor

Micro-supercapacitors(MSCs)are attractive electrochemical energy storage devices owing to their high power density and extended cycling stability.However,relatively low areal energy density still hinders their practical applications.Here,an asymmetric Mg ion MSC with promising high energy density is fabricated.Firstly,indium tin oxide(ITO)NWs were synthesized by chemical vapor deposition as the excellent current collector.Subsequently,nanostructured Mn_(3)O_(4)and Ppy@FeOOH were deposited on the laser-engraved interdigital structure ITO NWs electrodes as the positive and negative electrodes,respectively.Beneficial from the hierarchical micro-nano structures of active materials,high conductive electron transport pathways,and charge-balanced asymmetric electrodes,the obtained MSC possesses a high potential window of 2.2 V and a high areal capacitance of 107.3 mF cm^(-2)at 0.2 mA cm^(-2).The insitu XRD,VSM,and ex-situ XPS results reveal that the primary energy storage mechanism of Mg ions in negative FeOOH electrode is Mg ions de-/intercalation and phase transition reaction of FeOOH.Furthermore,the MSC exhibits a high specific energy density of 71.18μWh cm^(-2)at a power density of 0.22 mWh cm^(-2)and capacitance retention of 85%after 5000 cycles with unvaried Coulombic efficiency.These results suggest promising applications of our MSC in miniaturized energy storage devices.

Electromagnetic Transmission Characteristics of Y-Shaped and Y-Ring-Shaped Frequency Selective Fabrics

Asymmetrical Y-shaped and Y-ring-shaped frequency selective fabrics(FSFs) were proposed in this paper. They were prepared by computer engraving technology and tested in the anechoic chamber by using the free-space method. The test results of representative samples show that the resonance frequencies and the resonance peak or valley values in two polarization modes are not completely identical but the differentials are small, indicating that the influences of polarization modes are not significant. The transmission coefficient curves of Y-shaped and Y-ring-shaped FSFs with various size parameters are obviously different. For instance, as the unit size D increases by 4.0 mm, the resonance frequencies of patch FSFs decrease by 1.92 GHz and the resonance valleys increase by 12.32 dB. Different size parameters have dissimilar effects on the transmission characteristics and the corresponding influence laws should be analyzed concretely. The work could provide reference for the structural design and characteristics analysis of other FSFs.

Lavinia Fontana’s Galatea: Personification of Fortune and Venus

Lavinia Fontana’s(1552-1614)Galatea and Cherubs riding the Stormy Waves on a Sea Monster(aka Galatea)of 1590 is an intriguing mythological painting.Being painted on copper,it is a fine example of Lavinia’s exploration of new artistic techniques and materials as well as testimony to her bold artistic interpretations.Lavinia’s Galatea was part of a private collection in Bologna(Diletta Badeschi).This work fascinates the viewer with its erotic audacity and complex iconographical conceits.Recent scholarship by Daniele Benati,Fausto Gozzi,and Enrico Maria Dal Pozzolo assist in unraveling the meaning of this painting.In this essay there are additional interpretative suggestions.

A time sequential microfluid sensor with Tesla valve channels

The concentration of biomarkers in sweat can be used to evaluate human health,making efficient sweat sensing a focus of research.While flow channel design is often used to detect sweat velocity,it is rarely incorporated into the sensing of biomarkers,limiting the richness of sensing results.In this study,we report a time sequential sensing scheme for uric acid in sweat through a sequential design of Tesla valve channels.Graphene electrodes for detecting uric acid and directional Tesla valve flow channels were fabricated using laser engraving technology to realize time sequential sensing.The performance of the channels was verified through simulation.The time sequential detection of uric acid concentration in sweat can help researchers improve the establishment of human health management systems through flexible wearable devices.

Development of a microfluidic-chip system based on parallel flow for intensified Gd(Ⅲ)extraction from nitrate media using cationic extractant

Microfluidic solvent extraction （micro SX） of gadolinium was conducted using a mono- and diester mixture （MDEHPA） as the cationic extractant. A microfluidic Y-Y channel was fabricated using CO2- laser technique in a glass microchip used as the extraction system. Compared with batch extraction, extraction kinetic is found fast, and extraction equilibrium is attained within 15 s. Stoichiometry of the extracted complex is found to be Gd（NOs）3-3MDEHPA using log-log plot method. Additionally, the operating parameters and overall volumetric mass transfer coefficient （kLα） were investigated to determine the mass transfer performance. Optimal condition of microextraction for gadolinium using response surface methodology was determined （feed solutions 31 mg/L adjusted to pH value 2.5, extractant concentration 2.9 vol% and extraction time 13.5 s）. In optimal condition, gadolinium extraction yield is obtained 95.5%. Findings of this study approve simplicity, portability, effectiveness, swiftness, and environmental friendliness microfluidic solvent extraction process and reveal that micro SX is useful in the field of extraction strategic metals present at low concentrations, which are otherwise not technically amenable or economically feasible to extract using current traditional methods.

Regulation of cell locomotion by nanosecond-laser-induced hydroxyapatite patterning

Hydroxyapatite,an essential mineral in human bones composed mainly of calcium and phosphorus,is widely used to coat bone graft and implant surfaces for enhanced biocompatibility and bone formation.For a strong implant-bone bond,the bone-forming cells must not only adhere to the implant surface but also move to the surface requiring bone formation.However,strong adhesion tends to inhibit cell migration on the surface of hydroxyapatite.Herein,a cell migration highway pattern that can promote cell migration was prepared using a nanosecond laser on hydroxyapatite coating.The developed surface promoted bone-forming cell movement compared with the unpatterned hydroxyapatite surface,and the cell adhesion and movement speed could be controlled by adjusting the pattern width.Live-cell microscopy,cell tracking,and serum protein analysis revealed the fundamental principle of this phenomenon.These findings are applicable to hydroxyapatite-coated biomaterials and can be implemented easily by laser patterning without complicated processes.The cell migration highway can promote and control cell movement while maintaining the existing advantages of hydroxyapatite coatings.Furthermore,it can be applied to the surface treatment of not only implant materials directly bonded to bone but also various implanted biomaterials implanted that require cell movement control.

Graphene meta-aerogels:When sculpture aesthetic meets 1D/2D composite materials

The engraving technique has grown in parallel with our human civilization,along with the targeted materials evolving from stone and metals to wood.Benefiting from the blossom of nanotechnology,the bulky nicking tools have downsized themselves to a micro-/nanoscale,such as laser beams,and the materials have been extended from traditional hard ones to soft functional nanomaterials.When ancient sculpture art meets modern advanced micro-/nano fabrication techniques and low-dimensional materials,impossible materials are born,which will redefine the functional scope of well-developed materials.Recently,a team from Tsinghua University reported such fascinating materials,graphene-based meta-aerogels,that process excellent elasticity,ultralight specific weight(down to 0.1 mg·cm^(−3)),and superwide Poisson's ratio range(−0.95<v_(peak)<1.64)via facile and fast laser-engraving technique.

Engraved Floral Porcelain Jar

This engraved floral porcelainjar, enameled with red and blue,was excavated in Baoding of HebeiProvince in 1964. It stands 42.3 cmtall, with a circumference (at itswidest point) of 34 cm. The lid,