This study focuses on systematically revealing how cutting parameters influence the surface integrity of ball-end hard milled surface of AISI D2 steel and proposing optimization scheme from surface ...integrity, wear resistance and fatigue resistance perspective based on response surface methodology respectively. Results can be summarized into three aspects. Firstly, radial depth of cut with percent contribution ratio (PCR) 62.05% has a decisive influence on surface roughness, followed by spindle speed 13.25% and feed per tooth 6.63%. The work hardening degree was raised from 12.5% to 38.4% when spindle speed changed from 8000 rpm to 2000 rpm. Spindle speed and radial depth of cut are the most significant factor influencing residual stress. The PCR of spindle speed and radial depth of cut reached 73.47% and 18.63% for residual stress in feed direction, 47.11% and 37.51% in step-over direction, respectively. High residual compressive stress can be generated by lowering spindle speed and radial depth of cut benefiting from the aggravated squeeze between ball-end milling cutter and workpiece. Secondly, too small feed per tooth or too small radial depth of cut should be avoided from wear resistance point because though the surface microhardness can be improved, the surface quality will also be deteriorated. The combination of high spindle speed, small feed per tooth together with small radial depth of cut can meet the wear resistance and the machining efficiency requirement. Finally, a medium-sized cutting parameter combination should be adopted to realize satisfying material removal rate and fatigue resistance. This study can be used to guide the selection of cutting parameters during ball-end milling of hardened AISI D2 steel for dies/molds manufacturing industries.
Nitinol is well known as one difficult-to-machine alloy due to its poor machinability, which requires a large amount of cutting force and cutting temperature, resulting in poor surface roughness and ...strain hardening. The influence of the milling parameters on the surface roughness and strain hardening with orthogonal experiment is studied in this paper. It is found that cutting speed and feed rate have important influence on the surface roughness and strain hardening. When the cutting speed becomes larger, the surface roughness decreases, while the work hardening decreases first and then gets bigger. The surface roughness and work hardening increase gradually when the feed rate increases. However, the width of cut has little effect on the above surface roughness and strain hardening. The research shows that the medium range of cutting speed selection is better for the milling of NiTi shape memory alloy as used as medical implant materials that can achieve the minimal work hardening and smaller surface roughness.
The immune system of a host functions critically in shaping the composition of the microbiota, and some microbes are involved in regulating host endocrine system and development. However, whether the ...immune system acts on endocrine and development by shaping the composition of the microbiota remains unclear, and few molecular players or microbes involved in this process have been identified. In the current study, we found that RNA interference of a C-type lectin (HaCTL3) in the cotton bollworm Helicoverpa armigera suppresses ecdysone and juvenile hormone signaling, thus reducing larval body size and delaying pupation. Depletion of HaCTL3 also results in an increased abundance of Enterocuccus mundtii in the hemolymph, which may escape from the gut. Furthermore, HaCTL3 and its controlled antimicrobial peptides (attacin, lebocin, and gloverin) are involved in the clearance of E. mundtii from the hemolymph via phagocytosis or direct bactericidal activity. Injection of E. mundtii into larval hemocoel mimics HaCTL3-depleted phenotypes and suppresses ecdysone and juvenile hormone signaling. Taken together, we conclude that HaCTL3 maintains normal larval growth and development of H. armigera via suppressing the abundance of E. mundtii in the hemolymph. Our results provide the first evidence of an immune system acting on an endocrine system to modulate development via shaping the composition of microbiota in insect hemolymph. Thus, this study will deepen our understanding of the interaction between immunity and development.
Eighty-one samples from both shallow and deep aquifers were collected and analyzed to reveal groundwater hydrogeochemical characteristics and estimate groundwater quality suitability for irrigation ...and drinking purposes based on groundwater quality indexes models including the sodium adsorption ratio (SAR), residual sodium carbonate (RSC), solute sodium percentage (%Na), magnesium hazard (MH), permeability index (PI) and health risk model. The results from groundwater quality suitability assessment indicated that shallow groundwater in the most part of the study region was suitable for irrigation regardless of EC, RSC and MH, while groundwater from the deep aquifer was suitable for irrigation purpose in nearly all parts of the study region. 24.49% and 14.29% of the deep groundwater sampling locations presented high fluoride (F
−
) concentrations exceeded the Grade III value (1 mg/L) from Quality Standard for Groundwater of China and the maximum permissible value of 1.5 mg/L recommended by the WHO for drinking use, respectively. Non-carcinogens hazard quotient (HQ) values of NO
3
−
–N, NH
4
+
–N, NO
2
−
–N, Fe, and Mn with the exception of F
−
were all within the acceptable safety limit (HQ < 1). Efficient strategies and scientific decisions were suggested for groundwater resource protection and water quality improvements should be adopted for sustainable groundwater exploitation.
This paper describes the design of a precision bipolar junction transistor based temperature sensor implemented in standard 0.7-μm CMOS technology. It employs substrate p-n-ps as sensing elements, ...which makes it insensitive to the effects of mechanical (packaging) stress and facilitates the use of low-cost packaging technologies. The sensor outputs a duty-cycle-modulated signal, which can easily be interfaced to the digital world and, after low-pass filtering, to the analog world. In order to eliminate the errors caused by the component mismatch, chopping and dynamic element matching (DEM) techniques have been applied. The required component shuffling was done concurrently rather than sequentially, resulting in a fast DEM scheme that saves energy without degrading accuracy. After a single-temperature trim, the sensor's inaccuracy is ±0.1 °C (-20 to 60 °C) and ±0.3 °C (-45 to 130 °C), respectively. Measurements of sensors in different packages show that the package-induced shift is less than 0.1 °C. Measurements of eight sensors over 367 days show that their output drift is less than 6 mK. While dissipating only 200 μW, the sensor achieves a resolution of 3 mK (rms) in a 1.8-ms measurement time, and a state-of-the-art resolution figure of merit of 3.2 pJK 2 . This combination of high accuracy, high resolution, high speed, and low-energy consumption makes this sensor suited for commercial and industrial applications.
This paper presents the findings of experimental investigations into the effects of tool path strategies on fatigue life of high-speed ball-end-milled AISI H13 steel. Milling operations were ...conducted under three different tool path strategies with four levels of feed per tooth 0.1–0.4 mm/z. Fatigue life of machined samples was tested by three-point bending fatigue tests. Results show that the fatigue performance is susceptible to tool path strategies. Different tool path strategies bring the difference in microscopic stress concentration induced by the orientational surface topography and the effective residual stress defined as the residual stress component along the applied tensile stress direction. These two aspects can alter the real maximum tensile stress suffered by the milled surface and then influence the fatigue performance. Moreover, optimization methods for the tool path selection are put forward based on the findings that the effective residual stress has more significant influence on fatigue performance than the microscopic stress concentration and the more compressive the residual stress is, the longer the fatigue life will be. This study indicates that the fatigue performance for a ball-end-milled surface can be improved from the tool path control point of view.
Liver injury is a serious clinical syndrome that characterized by inflammatory response. Engeletin is known to have anti-inflammatory activity. However, the effects of engeletin on liver injury ...remain unclear. We aimed to assess the protective effect of engeletin on Lipopolysaccharide (LPS)/d-galactosamine (D-gal)-induced liver injury in mice. Engeletin was administered intraperitoneally 1 h before and 12 h after LPS/D-gal treatment. The results showed that engeletin treatment on LPS/D-gal-induced liver injury in mice have a significant protective effect, as confirmed by the attenuation of liver histopathologic changes, MPO activity, and serum AST and ALT levels. At the meanwhile, it also showed that engeletin inhibited the levels of IL-β and TNF-α in serum and liver tissues. Besides, engeletin blocked the activation of NF-κB induced by LPS/D-gal and induced the expression of PPAR-γ in a dose-dependently manner. These findings suggested that engeletin may have a protective effect against liver injury.
To establish the standardization process of acid-base balance analysis, analyze cases of acid-base balance disorder with the aid of acid-base balance coordinate graph.
The acid-base balance theory ...were reviewed systematically on recent research progress, and the important concepts, definitions, formulas, parameters, regularity and inference in the analysis of acid-base balance were studied. The analysis of acid-base balance disordered processes and steps were figured. The application of acid-base balance coordinate graph in the cases was introduced.
The method of "four parameters-four steps" analysis was put forward to analyze the acid-base balance disorders completely. "Four parameters" included pH, arterial partial pressure of carbon dioxide (PaCO
), HCO
and anion gap (AG). "Four steps" were outlined by following aspects: (1) according to the pH, PaCO
and HCO
, the primary or main types of acid-base balance disorder was determined; (2) primary or main types of acid-base disorder were used to choose the appr
With the continuous increase in the number of visually impaired individuals, it has become urgent to address the traffic challenges faced by this group. A blind guiding robot based on speed ...adaptation and visual recognition was designed to address this problem. The speed adaptation of the robot and the blind person is achieved through feedback control of the distance and speed. Traffic signals are identified using optimized visual recognition method based on YOLOv5 transfer learning, and man-machine interaction is realized by applying multi-module units such as real-time image, speech, and positioning. The experimental results show that the deviation between the relative distance between the man and machine and the set distance was controlled within 13.1%, the relative velocity deviation was controlled within 0.3 m/s, the accuracy of identifying traffic signals reached 91.88%, and when the man-machine distance gap is large, the robot can timely control the man-machine distance to the set distance within 0.7 s, which effectively ensured the travel safety of blind people and provide the groundwork for the practical application of guiding blind robots.
Smart power grid is a two-way interconnected network in which information plays a fundamental role in the process of energy transmission and distribution. The smart grid is based on combining ICT ...with the processing capabilities of computers and electrical systems to increase communication between users. However, smart grids are exposed to a variety of malicious cyber-attacks that can lead to the destruction of basic infrastructure and disrupt communication between the grid and users. Meanwhile, by authenticating the authenticated users, cyber-security can be created in the smart grid. One of the main components of a smart power grid is smart meters. However, to maintain security in a communication, smart meter authentication alone is not enough and it must be ensured that the electricity company’s server is not forgery. Therefore, there is a need for two-way authentication between the smart meter on the home side and the electricity company server. The present work provides a key management layout (based on the elliptic curve cryptography) with two-way authentication for communication outside the home area network The proposed solution is two-way authentication among the smart meter and the security associate in the power company. In other words, the proposed methodology creates a solution to establish a connection between valid users and the smart grid. The proposed protocol evaluates the behavior of cyber-attacks on the smart grid. Attacks such as man-in the middle attacks and retransmission attacks are considered. It was found that, the proposed methodology improves the reliance between smart grid and authenticated users with the increase of secure communications. Moreover, the proposed protocol can prevent an extensive experiment attack. The results also showed that, as the false factor increases, the detection time by the proposed algorithm increases. As the false factor increases from 0.1 to 0.3, the detection time increases by 1.4 s.
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