Digital Processing Technology Research Articles

Repairability of a 3D printed denture base polymer: Effects of surface treatment and artificial aging on the shear bond strength

ObjectivesThe present study aimed to evaluate the repairability of a 3D printed denture base material. The effects of surface treatments and artificial aging on the shear bond strength (SBS) were investigated. MethodsA total of 224 specimens were printed by digital light processing technology (Rapid Shape D30II) using a 3D printing denture base material (FREEPRINT denture). To evaluate the repairability, the SBS and failure modes were measured after surface treatment and artificial aging. Specifically, half of the specimens were further performed with thermocycling (5–55 °C, 5000 cycles) for artificial aging. The aged and non-aged specimens were further divided into four subgroups (n = 28) to simulate a denture base repair with one of the following treatments: control (without surface treatment), monomer (applying methylmethacrylate for 120 s), P600 (grinding with P600 silicon carbide paper) and sandblasting (blasted with 125 μm aluminum oxide with 2 bar), respectively. Surface roughness was measured (n = 6) and surface topography was observed by scanning electron microscopy (n = 2). A test rod was built on the sample surface using the same 3D printing material. Afterward, all specimens further underwent thermocycling (5–55 °C, 10,000 cycles). ResultsFor non-aged groups, no significant differences in SBS could be found (p < 0.05), and bondings failed cohesively in the denture base material. Regarding the aged control and monomer group, adhesive failures at the interface were primarily observed, and SBS values were statistically lower than those of the other groups (p < 0.05). ConclusionsThe 3D printed denture base material exhibited favorable repairability. For the realignment surface, the SBS at the bonding interface is satisfying and additional surface treatments could be not necessary. In contrast, the aged surface could significantly decrease the SBS; hence subtractive surface treatments are highly recommended.

A highly stretchable and intrinsically self-healing strain sensor produced by 3D printing

ABSTRACT One common issue when implementing wearable strain sensors for health-monitoring is the limited service time when they are inevitably subjected to mechanical operation in practical applications. Therefore, integrating multi-functionality with reliable performance is a long-term pursing target. To this end, we have developed a promising strain sensor utilising a facile 3D printing technology of digital light processing (DLP), thereby simultaneously realising super-high stretchability and intrinsic self-healing ability. Owing to the incorporation of carboxyl multi-walled carbon nanotubes (c-CNTs), the over-curing of the N-acryloylmorpholine (ACMO) resin was adequately mitigated, and good electrical conductivity of the nanocomposite was obtained. On the basis of multi-functionality, the strain sensor before and after self-healing can be applied for real-time and accurate detection of human activities. Therefore, it is expected that the highly stretchable and intrinsically self-healing strain sensor will have promising applications in wearable electronics, personal health care, etc.

Mechanical properties of 3D printed ceramic cellular materials with triply periodic minimal surface architectures

In this study, four types of triply periodic minimal surface (TPMS) were implemented to create cellular ceramics via digital light processing (DLP) technology, namely p-cell, gyroid, IWP and s14. The mechanical properties of these TPMS structures were investigated experimentally. Results showed that compressive strength of TPMS structures increases with relative density. IWP and s14 structures exhibit similar mechanical response under stress. In general, all TPMS structures can sustain >2% strain without failure and the compressive strength followed the order of s14 > IWP > gyroid > p-cell. The s14 structure can reach a high compressive strength of 105 MPa at a structural density of 30.5 % while gyroid structure can provide a compressive strength of 5.6 MPa at a very low structural density of 6.7 %. The porosity dependence of Young’s modulus of sintered zirconia TPMS demonstrated that the Pabst-Gregorova exponential relation can provide a better prediction than the classical Gibson-Ashby model.

(Invited) Material Development and Equipment Improvement for 3D Gel Printing Using a Commercially-Available Stereolithography Printer

Hydrogels are known as a soft and water-rich material, and they are widely applied in the medical and industrial fields. On the other hand, when a liquid material is poured into a mold to make a gel, it is generally difficult to form a complicated shape due to the shape restriction included in the mold. To overcome this challenge, we have independently developed the 3D gel printer "SWIM-ER". This gel printing can make very complex structures that is unable to create by the hydrogel molding process. The our previous works includes soft robots for teaching, research, and surgical simulation and applications of 3D-printed organ models in hydrogel.However, it should be pointed out that due to the high economic cost, this printer is not popular. This study proposes an inexpensive gel printing technology using a commercially available stereolithography 3D printer equipped with liquid crystal display (LCD) or digital light processing (DLP) technology for UV irradiation. The price of a commercial 3D printer for general use ($500) is much cheaper than the price of a 3D gel printer. We have confirmed that our proposed method can perform three-dimensional modeling of gel by photopolymerization reaction under excitation of 405 nm. Figure 1

X—Ray Digital Image Advanced Processing and Buffer Layer Defect Intelligent Identification of Power Cable

With the rapid modernization of the city, power cable has been widely used in the process of urban construction. In the course of cable operation, cable faults become more and more frequent, which has a great impact on national economy and people’s life. The method of digital X-ray imaging can realize the nondestructive testing of power cable body and obtain clear and intuitive X-ray digital image. But it lacks the advanced processing and defect recognition method of X-ray digital image, and can not directly detect and identify the cable body and defect from the original digital image. Therefore, this paper studies the power cable X-ray digital image advanced processing and buffer layer defect intelligent identification technology. By using gray scale processing technology, the original image gray scale range is compressed to the human eye identifiable range, and then the defect identification is carried out. Then the traditional convolution neural network CNN and the full convolution neural network FCN are used to train the image data to realize the intelligent recognition of the power cable buffer layer defect. The research shows that compared with the traditional convolution neural network CNN, the full convolution neural network FCN proposed in this paper has more clear and intuitive recognition effect.

Stereolithography-based additive manufacturing of lightweight and high-strength Cf/SiC ceramics

Digital light processing technology (DLP) is an effective additive manufacturing method to fabricate ceramic components with high precision and complicated structure. Here, a novel strategy to prepare chopped carbon fibers (Cf)/SiC ceramic composites through stereolithography Cf combined with liquid silicon infiltration is presented. The photosensitive suspension including Cf was prepared and Cf preforms with convoluted geometrical shapes were manufactured by DLP technology. The 3D-architectured bodies possessed high printing stableness and accuracy with the forming deviation of less than 5%. Moreover, the tightly bonded adjacent layers can contribute to the synergistic effect from curing adhesion of photosensitive resin and crisscrossed pinning of chopped carbon fibers. As-prepared components after liquid silicon infiltration were dense and exhibited maximum flexural strength of 262.6 MPa. This strategy demonstrates a promising prospect and tantalizing possibility to fabricate SiC ceramic composites with complex shapes and structures.

Marine controlled-source electromagnetic method data de-noising based on compressive sensing

The marine controlled-source electromagnetic method (CSEM) is a detection technology predominately used for hydrocarbon exploration and reservoir estimation. However, the signal can be easily contaminated by different types of noises. De-noising is a crucial procedure for improving data accuracy and credibility. Presently, frequently used de-noising methods are the classical windowed Fourier transform and wavelet transform methods. These methods are only effective for Gaussian white noises, and they are not suitable for marine CSEM data. Compressive sensing (CS), a new digital data processing technology, is a new method for solving this problem. By using the orthogonal matching pursuit algorithm with different dictionaries, CS provides an effective way to reduce noise impacts. This work presents the first application of CS to marine CSEM data de-noising, and the outcomes under different dictionaries are compared with those of traditional methods. The de-noising performance of CS is closely related to the selected dictionary, and we separately analyze the results of the discrete sine transform dictionary, wavelet dictionary, and three merged dictionaries. The results illustrate that the CS algorithm under certain dictionaries performs better than the windowed Fourier transform and wavelet transform methods.

Digital twin process and simulation operation control technology for intelligent manufacturing unit

In the manufacturing process, the intelligent manufacturing unit will produce unexpected situations with different forms and a large amount of data. How to control the intelligent manufacturing unit more intuitively and effectively control the operation and control of the trolley is an urgent problem to be solved. This paper proposes a digital twin process and simulation operation control technology for intelligent manufacturing units, including virtual workshop and actual workshop real-time mapping technology and digital twin-based simulation control technology. Through these two technical means, intelligent manufacturing unit realized visual real-time management and control. In the end, the author designed an intelligent manufacturing unit management system to successfully verify the effectiveness of the above technology.

The Effect of Parameters on the Process of Making Objects with Rapid Prototyping Digital Light Processing Technology on the Bending Stress

The world is currently entering the era of the industrial revolution of 4.0. The era in which the occurrence of disruptive technology. The main purpose of this existence of the industrial revolution to create stability in the distribution of goods and necessities. Broadly speaking, there are some benefits that can be posed by the presence of the industrial revolution 4.0 is encouraging research, customization, and optimization. In addition, there are several challenges to be faced in the industrial revolution was the first IE 4.0 security, the second is the capital, and then a third that is employment, and the fourth is privacy. A method that can respond to these challenges is additive manufacturing using SLA-DLP 3D Printing. The making of objects utilizing CAD data that have been made in advance. This research aims to know the effect of object making process parameters with digital light processing rapid prototyping technology on bending stress. The parameters investigated is the layer thickness and the exposure time. Test specimens made of a material with liquid photopolymer resin refer to ASTM D 790 using SLA-DLP 3D Printer. Measurement results in data analysis using ANOVA design with type 2 factorial design model and level 1 factorial interactions assisted by software Design Expert trial version. The results of the ANOVA is known that factors significantly (α = 0.001), to effect of object making process parameters with digital light processing rapid prototyping technology on bending stress., that are the layer thickness=10%, exposure time=2%, interaction layer thickness and exposure time=87%.

DLP printing photocurable chitosan to build bio-constructs for tissue engineering

In this study, we provide a photocurable chitosan bioink (CHI-MA), which can be used for the digital light processing (DLP) technology. The CHI-MA precursors were facilely synthesized by grafting chitosan molecular chains with methacryloyl groups. We investigated the effect of parameters, including the concentration and substitution degree (DS) of CHI-MA, on the rheology and the photocuring of bioinks and the mechanical property of photo-crosslinked gels. Using the CHI-MA with a high DS (33.6 %), the curing time to print a 150 μm thick hydrogel layer can be controlled within a reasonable short time period. Additionally, the cytotoxicity test shows that both the photocuring process and the photo-crosslinked hydrogels exhibit an excellent biocompatibility. Through the DLP printing, the CHI-MA bioink can be processed into complex 3D hydrogel structures with high-resolution, high-fidelity and good biocompatibility. It indicates that the photocurable CHI-MA would be a good bioink suitable for the DLP printing.

Preparation and biological evaluation of ZrO2 all-ceramic teeth by DLP technology

Personalized zirconium dioxide (ZrO2) all-ceramic teeth are expected to be widely used in the field of oral restoration. Here, ZrO2 all-ceramic teeth were fabricated for biological engineering by photosensitive resin based digital light processing (DLP) technology. When sintered at 1500 °C for 3 h, dense ZrO2 ceramics were obtained with relative density of 98.02 ± 0.32%, Vickers hardness of 12.62 ± 0.15 GPa and fracture toughness of 6.11 ± 0.36 MPa∙m1/2, which were close to those of the ZrO2 ceramics prepared by dry pressing. To confirm whether the prepared ZrO2 ceramics possessed good biosafety, in vitro biological experiments were further performed with rat bone marrow mesenchymal stem cells (rBMSCs) and preferable cell attachment was observed at the initial stages. Results illustrated that the compositions with cytotoxicity in green samples were completely decomposed after debinding and sintering process, and the ZrO2 ceramics could provide an ideal biocompatible environment for mesenchymal stem cells. This study shows that ZrO2 all-ceramic teeth with personalized structure prepared by DLP technology have good mechanical properties and biocompatibility, exhibiting strong potential in the field of oral restoration.

Three Dimensional Maskless Ultraviolet Exposure System Based on Digital Light Processing

This paper reports the development of a three dimension maskless photolithography system with an oblique scanning method based on digital light processing technology. The system consists of a UV light source, a digital micromirror device (DMD), a microlens/pinhole array, two optical projection lenses, and a three-axis (xyz) servo-controlled stage. The optical system can form a rectangular array of UV spots with a diameter of few μm directly on the surface of a sample sitting on the stage. A photoresist (PR) layer is coated on the sample surface. Using an oblique scanning approach, the whole area of PR layer can be exposed by this UV exposure system in a maskless manner. Since the energy intensity of each UV spot can be independently modulated by a corresponding group of micromirrors in the DMD, and a three-dimensional (3D) UV dosage distribution can be achieved through computer programming on the DMD and the xyz stage. After developing processes, 3D PR microstructures with arbitrary patterns and/or surface profiles can be readily formed by this maskless lithography system. Experimental results will be addressed as well as potential applications for 2D and 3D microfabrication.

Demand management by active consumers in intelligent electric power systems

The approaches to demand management by active consumers through forming a given schedule of power consumption in the required period of time based on the solution of the optimization problem in the form of maximizing the power of connected controlled electric receivers of various types are presented. The model of demand management by active consumers is justified, taking into account the following factors: load sensitivity for connecting a transformer substation to a change in consumer load; load priority; consistent load reduction levels with flexible performance and power control; permissible set of electric receivers in accordance with the technological process, network schedule, other logical conditions corresponding to adjacency lists. An algorithm has been developed for limiting power on the part of active consumers based on the widespread use of digital data processing technologies, modern technical means of measurement, control and switching of end consumers in real time. The presented research results indicate the validity of the demand management method by active consumers in the normal mode of intelligent electric power systems and the possibility of its practical implementation in an industrial enterprise with reference to the technological process.

Demand management by active consumers in intelligent electric power systems

The approaches to demand management by active consumers through forming a given schedule of power consumption in the required period of time based on the solution of the optimization problem in the form of maximizing the power of connected controlled electric receivers of various types are presented. The model of demand management by active consumers is justified, taking into account the following factors: load sensitivity for connecting a transformer substation to a change in consumer load; load priority; consistent load reduction levels with flexible performance and power control; permissible set of electric receivers in accordance with the technological process, network schedule, other logical conditions corresponding to adjacency lists. An algorithm has been developed for limiting power on the part of active consumers based on the widespread use of digital data processing technologies, modern technical means of measurement, control and switching of end consumers in real time. The presented research results indicate the validity of the demand management method by active consumers in the normal mode of intelligent electric power systems and the possibility of its practical implementation in an industrial enterprise with reference to the technological process.

Additive manufacturing of SiBCN/Si3N4w composites from preceramic polymers by digital light processing.

The application of advanced ceramic materials is limited by their brittleness and complicated manufacturing methods. Three-dimensional (3D) printing has emerged as a new method for the fabrication of complex-shaped ceramics. Herein, a type of printable slurry composed of SiBCN preceramic polymers and high-volume fractions of Si3N4 whiskers (up to 60 wt% of polymer) was prepared, and subsequently printed via digital light processing (DLP) technology. We successfully manufactured complex-structured ceramic composites and achieved high bending strength (∼180 MPa). The linear shrinkage and mass loss of the ceramic material were both significantly reduced after the introduction of whiskers. The properties and structure of the printed parts pyrolyzed at different temperatures were compared, and the relationship between the microstructure and mechanical properties discussed.

The design of embedded image teaching systems based on ARM technology

With the continuous development of multimedia and speech teaching laboratory in colleges and universities, and the application of digital processing technology, digital voice teaching equipment is attracting more and more attention from domestic universities and instrument manufacturers. Based on the core technology of ARM and DSP dual core technology, the theoretical analysis of digital language learning system is carried out, and the student terminal circuit and teaching software system are designed in detail, and the function and technical index of the whole system are tested. The test results show that the digital speech learning system constructed by the student terminal controlled by ARM and DSP binuclear is fully satisfied with the actual language teaching requirements.

The design of embedded image teaching systems based on ARM technology

With the continuous development of multimedia and speech teaching laboratory in colleges and universities, and the application of digital processing technology, digital voice teaching equipment is ...

Single-step 3D-printed integrated optical system and its implementation for a sensing application using digital light processing technology.

This study proposes a single-step integrated optical fabrication scheme utilizing a 3D printer using digital light processing technology. Strong light confinement in the fabricated structure is realized through the introduction of an elevated (tower-shaped) waveguide in a transparent photosensitive resin (PX-8880). The fabrication is optimized to maximize light confinement through varying the dimensions of the guiding region and the tower structure. Benefiting from the surface roughness produced by the slicing process in the 3D printing (50 µm resolution), the fabricated structure was tested for vapor sensing. Obvious intensity dynamics have been reported due to the change of the optical scattering due to the presence of vapor as well as polymer vapor interaction. Though the reported response time is long, further optimization can lead to practical operation time.

Study on two-dimensional code recognition algorithm in non-uniform illumination based on digital images processing technology

It is possible that the shaded area was mistakenly identified based on digital images processing technology with non-uniform illumination. The binarization algorithm of two-dimensional code was optimized to this problem. The local area threshold of the image and the pixel-by pixel sliding calculation are used to eliminate the influence of the illumination on the image, thereby improving the recognition rate of the two-dimensional code image which contains the shadow. Experimental result indicate that the method has a stronger adaptability to images with shaded areas, especially for unilateral shadows which are less ideal for block resolution. Compared with the classical global Ostu algorithm, the recognition rate of the image is increased by about 3 times.

Features of the Development of the Digital Educational Environment in Russia

Goal of the investigation: This article aims to distinguish the characteristics of the development of the digital educational environment in Russia in the context of the global digitalization process, and to identify threats to information security. Methodology: The leading method for studying this problem is a comparative analysis of the level of evolution of the digital administration in various nations of the world, which passes to comprehensively estimate the obstacle of receiving the learning and informative space as a portion in the sustainable expansion of the Russian economy. Results: The authors revealed the peculiarities of the Russian “digitalization” management system, which is still distinguished by spontaneity and the lack of a coordinated action program on the part of the state. It was revealed that Russia has the necessary potential for the further development of the digital economy: the scientific and intellectual base, a good level of secondary and higher technical education. The article substantiates the results of the development of the Russian digital educational environment: a data source (portal) has been created that is convenient to all levels of residents and stores each user with entrance to online classes for all levels of training and online support for mastering general education subjects; an infrastructure has been created to train teachers and administrative staff, to spread the experience of introducing successful methods and practices of online learning, to track the dynamics of creating a digital educational environment; and a system of advanced training for teachers in the development, use and examination of online courses has been created. Applications of this study: The materials of the article can be useful to relevant state and economic institutions for the formation of a mechanism for informatization of the country's development management system and education in particular, which is part of certain development strategies and programs; researchers of socio-economic processes associated with the development of the information society and the economy, and the increasing distribution of digital data processing technologies. The analysis of the digitalization process in the country and the world allowed us to identify problems that require close attention and finding solutions for the implementation of project activities for the formation of a modern digital educational environment in the Russian Federation. Novelty/Originality of this study: The novelty and originality of the study lies in the fact that for the first time it offers a comprehensive approach to assessing the specifics and factors of the digitalization process in the educational space of the country, developing mechanisms to reduce threats to information security by developing a system for identifying users, technical controls, and improving the legislative framework.