Tip Width Research Articles

Broadband and easily fabricated double-tip edge coupler based on thin-film lithium niobate platform

Due to the significant difference in spot size between lithium-niobate-on-insulator (LNOI) waveguide and fiber, there is a substantial coupling loss between them, which limits the interconnection and application of LN photonic chips. Although some LNOI edge couplers have been designed and fabricated with low coupling loss between chip and fiber, they require high etching accuracy. In this paper, a low-loss, broadband and easily fabricated edge coupler is designed and fabricated on the LNOI platform. To reduce the etching requirement for tip width, a design has been adopted with symmetrical double tips at the edge. Additionally, a multimode interferometer (MMI) is introduced to ensure large fabrication tolerance. The proposed design only requires a single full etching step, significantly reducing stringent requirements for process with high precise. Experimental results demonstrate that the device exhibits a coupling loss less than 3.5 dB/facet in the wavelength range of 1500–1640 nm, while achieving a low coupling loss of 2.71 dB/facet at 1550 nm.

Fabrication of microneedles using wire electric discharge machining and improving surface quality by electrochemical polishing

Microneedle (MN) arrays have many applications in biomedical engineering to deliver drugs transdermally or extract biomarkers from the interstitial fluid from the human skin. Several methods have been developed to fabricate different sizes and shapes of MN using polymers, ceramics and metals. However, most of these methods require expensive sophisticated machines and clean room facilities. So, it is difficult to fabricate microneedle arrays in large quantities at a reasonable cost. This study reports the fabrication of a high-quality stainless steel master pattern for an MN array using a wire-cut electric discharge machining process followed by electrochemical polishing (ECP). Different densities of a 5 × 5 array of microneedles with pyramidal shapes were fabricated by machining channels onto the workpiece surface in a criss-cross pattern. A systematic experimental study was carried out with reference to the offset between the two consecutive channel faces and the depth of channels. The output parameters are MN height (MNH), MN base (MNBW) and tip width (MNTW). The average needle tip width, base width, and height of microneedles were found to be 55.3 ± 5 µm, 679.8 ± 10 µm, and 914.7 ± 19 µm. Finally, the sharpness of the MN tips and the overall surface finish of the MN array were improved with ECP. The reductions in MNH, MNBW, and MNTW were reported to be −18.3%, −9.7%, and −95.4%, respectively, with a final tip width of 2.55 ± 1.62 µm. The MNs’ tip angle was reported to be 32.52° ± 1.56.

Cracking modes and force dynamics in the insertion of neural probes into hydrogel brain phantom

Objective. The insertion of penetrating neural probes into the brain is crucial for advancing neuroscience, yet it involves various inherent risks. Prototype probes are typically inserted into hydrogel-based brain phantoms and the mechanical responses are analyzed in order to inform the insertion mechanics during in vivo implantation. However, the underlying mechanism of the insertion dynamics of neural probes in hydrogel brain phantoms, particularly the phenomenon of cracking, remains insufficiently understood. This knowledge gap leads to misinterpretations and discrepancies when comparing results obtained from phantom studies to those observed under the in vivo conditions. This study aims to elucidate the impact of probe sharpness and dimensions on the cracking mechanisms and insertion dynamics characterized during the insertion of probes in hydrogel phantoms. Approach. The insertion of dummy probes with different shank shapes defined by the tip angle, width, and thickness is systematically studied. The insertion-induced cracks in the transparent hydrogel were accentuated by an immiscible dye, tracked by in situ imaging, and the corresponding insertion force was recorded. Three-dimensional finite element analysis models were developed to obtain the contact stress between the probe tip and the phantom. Main results. The findings reveal a dual pattern: for sharp, slender probes, the insertion forces remain consistently low during the insertion process, owing to continuously propagating straight cracks that align with the insertion direction. In contrast, blunt, thick probes induce large forces that increase rapidly with escalating insertion depth, mainly due to the formation of branched crack with a conical cracking surface, and the subsequent internal compression. This interpretation challenges the traditional understanding that neglects the difference in the cracking modes and regards increased frictional force as the sole factor contributing to higher insertion forces. The critical probe sharpness factors separating straight and branched cracking is identified experimentally, and a preliminary explanation of the transition between the two cracking modes is derived from three-dimensional finite element analysis. Significance. This study presents, for the first time, the mechanism underlying two distinct cracking modes during the insertion of neural probes into hydrogel brain phantoms. The correlations between the cracking modes and the insertion force dynamics, as well as the effects of the probe sharpness were established, offering insights into the design of neural probes via phantom studies and informing future investigations into cracking phenomena in brain tissue during probe implantations.

Titanium dioxide nanoparticles (TiO2-NPs) effect on germination and morphological parameters in alfalfa, tomato, and pepper

Titanium dioxide nanoparticles are used in different processes, derived from this their presence in wastewater is common, concentrating in residual sludge. These residues are used as agricultural soil improvers, being a source of crop exposure. In this study, the effect of TiO2-NPs (450, 900, and 1800 mg L-1) on the germination of alfalfa, tomato, and pepper seeds was evaluated. The germination parameters were not different (p > 0.05) except for, the seed vigor index in alfalfa and pepper, and the mean germination time in tomato. The germination index was below 80% in 450 mg L-1 in tomato, which showed moderate phytotoxicity. Morphological modifications with differences (p < 0.05) were found in the three crops, mainly in the root. In tomatoes, the length of the main root, root hairs, and the width of the root tip were reduced but increased the width of the main root, piliferous zone, and the length of root hairs were. For alfalfa, root length and number of secondary roots augment. However, the stem, root tip width, and root villi were reduced. Finally, for pepper, the length, and width of the root and the piliferous zone were modified. Additionally, a concerning trend has been observed in the length of root hairs. TiO2-NPs affected germination and morphology in alfalfa, tomato and pepper seeds differently. Tomato was most negatively affected, with reduced root length and width. Alfalfa showed mixed effects, with positive impacts on some parameters but negatives on others. Pepper seeds responded positively overall, with improved germination and root length, despite some impacts on root morphology.

Optimizing cutter wear in TBM operations through numerical analysis of enhanced rock-cutting interaction

The inevitable wear and degradation of disc cutters during the rock-crushing process significantly impacts the efficacy, timeline, and cost-effectiveness of tunnel construction. Optimizing cutter arrangements and adjusting suitable excavation parameters are crucial to reducing cutter wear in Tunnel Boring Machine (TBM) operations. This study probes the interaction between disc cutters and rock, employing an enhanced Bonding model to more accurately depict the failure behavior of rock specimens. Numerical simulations of the rock-breaking process using two disc cutters were conducted, focusing on highly influential excavation parameters—penetration depth (3, 5, 7, 9 mm) and cutter arrangements—tip width (14, 17, 20, 23 mm) and cutter spacing (50, 65, 80, 95, 110 mm). These simulations analyzed the impact of various factors on cutter force, wear, specific energy of rock breaking, and crushing unit rock cutter wear. The results show that increased penetration depth leads to higher cutter force and wear, with specific energy and unit wear remaining low when penetration is less than 5 mm. A larger cutter tip width incurs higher forces and wear of the first cutter, but when the tip width exceeds 20 mm, the force and wear of the second cutter will be reduced. Optimal specific energy for rock breaking and unit wear of rock volume were identified within a cutter spacing range of 80 to 95 mm. These findings can facilitate the analysis of how excavation parameters and cutter arrangements affect wear behavior, offering superior construction recommendations.

Nasal profile changes after LeFort I osteotomy (maxillary advancement) with and without ANS reduction in class III skeletal patients: a study protocol for a randomized clinical trial

BackgroundDentofacial malformation is a common condition that affects a significant portion of the population, resulting in functional and aesthetic defects. Orthognathic surgeries, such as LeFort I osteotomy, are performed to correct these abnormalities. However, the impact of these surgeries on nasal profile changes remains unclear. Additionally, the role of anterior nasal spine (ANS) reduction in maxillary advancement surgeries of 3–5 mm range is yet to be determined. This study aims to investigate the effect of ANS reduction on soft tissue profile changes following LeFort I osteotomy with a maxillary advancement range of 3–5 mm in class III skeletal patients. The hypothesis is that the changes in nasolabial angle and upper lip length will not significantly differ between patients who undergo LeFort I osteotomy with and without ANS reduction.Method and designThis study is designed as a randomized controlled trial. A total of 26 class III skeletal patients with maxillofacial abnormalities will be recruited from the maxillofacial clinic of Bu-Ali and Farahikhtegan Hospitals in Tehran, Iran. Patients meeting the inclusion criteria will be randomly assigned to two groups: one group will undergo LeFort I osteotomy with ANS reduction, and the other group will undergo LeFort I osteotomy without ANS reduction. The soft tissue profile changes, specifically the nasolabial angle and upper lip length, will be evaluated and compared between the two groups.DiscussionAchieving facial harmony through orthognathic surgery requires careful planning and consideration of the impact on surrounding soft tissue. The primary objective is to predict and plan for the effects on the nasolabial region. LeFort I osteotomy is a common procedure used to correct dentofacial deformities, particularly in class III patients. Maxillary advancement during this surgery can lead to changes in nasal tip position, width, and rotation, potentially due to repositioning of the anterior nasal spine and soft tissue dissection. In this study, soft tissue changes will be assessed in non-growing class III patients using cephalometric radiographs. The impact of reducing the anterior nasal spine (ANS) on nasal profile changes will be investigated for maxillary advancements of 3–5 mm. Objective measurements and patient-reported outcomes will be evaluated to gain insights into the aesthetic outcomes of orthognathic surgery. The findings will provide valuable guidance for treatment decisions and alternative options based on expected nasal profile changes.Trial registrationThis project was registered at The Iranian Registry of Clinical Trials (Identifier No. IRCT20210928052625N1, Website: https://www.irct.ir/trial/59171) and Open Science Framework (OSF) (Registration https://doi.org/10.17605/OSF.IO/X3HD4). 2021-06-09.

Introducing a new rock abrasivity index using a scaled down disc cutter

Rock abrasivity influences wear of cutting tools and consequently, performance of mechanized tunneling machines. Several methods have been proposed to evaluate rock abrasivity in recent decades, each one has its own advantages. In this paper, a new method is introduced to estimate wear of disc cutters based on rock cutting tests using scaled down discs (i.e. 54 and 72 ​mm diameter). The discs are made of H13 steel, which is a common steel type in producing real-scale discs, with hardness of 32 and 54 HRC. The small-scale linear rock cutting machine and a new abrasion test apparatus, namely University of Tehran abrasivity test machine, are utilized to perform the tests. Tip width of the worn discs is monitored and presented as the function of the accumulated test run to classify the rock abrasion. Abrasivity tests show that by increasing the uniaxial compressive strength (UCS) of the rock samples, wear rate is doubled gradually that reveals the sensitivity of the test procedure to the main parameters affecting the abrasivity of hard rocks. For the rocks with the highest UCS, the normal wear stops after performing 5 to 10 rounds of the tests, and then, deformation of the disc tip is detectable. Two abrasivity indices are defined based on the abrasivity tests results and their correlations with Cerchar Abrasivity Index (CAI) and UCS are established. Comparison of the established correlations in this study with previous investigations demonstrates the sensitivity of the indices to the parameters affecting wear of the disc cutters and repeatability of the outputs obtained from abrasivity tests using scaled down discs. Findings of this study can be used to enhance the accuracy of rock abrasivity classifications.

Ultrasonic Evaluation of the Asian Nasal Soft Tissue Envelope.

The thickness of the nasal soft tissue envelope (STE) plays a crucial role in the final rhinoplasty results. The Asian nasal contour is typically characterized by a thicker STE and broader nasal tip, but objective data are lacking. The purpose of this study was to objectively measure nasal dermal thickness and overall STE thickness and to determine any demographic differences. From July to September 2023, 110 patients presenting for consultation underwent ultrasound evaluation of their nasal STE. STE thickness was measured at predetermined subsites and compared with published data on white patients. The thickness of the STE in Asian patients was greater than that in white patients. The STE was thickest at the supratip (mean [SD]), (4.88 [0.74]mm) rather than at the nasion and thinnest at the rhinion (2.25 [0.51]mm). The nasal tip (4.07 [0.72]mm) showed comparable STE thickness with the nasion (4.13 [0.72]mm) but had a significantly thicker dermis than the nasion (2.35 ± 0.49mm vs. 1.35 ± 0.35mm, P < 0.05). Male sex and higher BMI tended to be correlated with a thicker nasal STE, but age did not show any relationship. A thicker nasal tip STE showed significantly greater nasal tip width and nasal alar thickness. STE thickness at different nasal subsites varies and affects external nasal contour and rhinoplasty outcomes. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Evaluation of the effect of TBM disc cutter wear on rock cutting efficiency

AbstractThe geometry of the disc cutter is one of the most important factors in the rock cutting process of mechanized tunnel boring machines (TBMs). However, during excavation, the optimal conditions of the disc cutter are not constant due to disc cutter wear. One of the most significant consequences of cutter wear is the increase in the contact area of the disc cutter with the rock so when the wear of the cutter exceeds its maximum limits, it should be replaced. Therefore, this study will examine the effect of disc cutter wear on TBM operational parameters such as thrust force, net penetration rate, and specific energy. In order to achieve this, six types of worn 17“ disc cutters have been studied graphically, and a method for calculating the surface of contact between the disc cutter and rock as a function of the cutter tip width has been developed. Moreover, a new equation has been proposed to predict normal and rolling cutting forces whose results are in good agreement with the reported laboratory values. As a final step, the hard rock TBM parameters of the Kani Sib water conveyance tunnel have been studied after replacement of worn disc cutters. The results show that replacing the worn disc cutters leads to an increase in penetration rate and a decrease in thrust force, resulting in an increase in specific penetration. On average, specific penetration increases by ≈35 %.

Enhanced flow induced vibration piezoelectric energy harvesting performance by optimizing tapered beam

This paper proposes a tapered cantilever beam flow induced vibration piezoelectric energy harvester, for optimizing the tapered beam and improving the output characteristics. The physical model of the tapered beam harvester is conceived, a two-dimensional CFD simulation model is established, and experimental validation as well as investigation is conducted. The output voltage and displacement response of the harvesters with various tapered beams are explored. The results show that the tapered beam possesses more uniform strain distribution and larger equivalent stiffness, and increasing the fixed end width results in enhancing output voltage and reducing vibration displacement. The optimal tapered beam with a tip width of 25 mm and fixed end width of 45 mm is obtained. The maximum output voltages of the tapered beam VIVPEH and GPEH are increased by 58.30% and 33.16% over the rectangular beam, respectively. The vibration displacements of the tapered beam VIVPEH and GPEH are reduced by 18.31% and 25.12% over the rectangular beam, respectively. The tapered effect in the flow field reduces the vortex shedding distance, increases the shedding frequency, enhances the aerodynamic forces, and thus improves the energy harvesting performance. This work lays the important foundation for exploring the cantilever beam flow induced vibration harvester system.

Prospective study of nasal growth in bilateral cleft lip and palate patients after naso-alveolar moulding and primary columella lengthening compared to controls at 5, 10 and 20 years.

A short columella, wide nostrils and a flat nasal tip are common features in patients with bilateral complete cleft lip and palate (BCLP). The objective of this study was to evaluate nasal morphology during growth in patients treated with naso-alveolar moulding (NAM) and primary surgical columella lengthening (PCL) compared with matched non-cleft individuals. Prospective longitudinal case-control study. Thirty-four consecutively treated BCLP patients at 5 and 10 years and at the end of growth (19.7 ± 2.0 years) were compared through normalized photogrammetry to a control of 34 age and sex-matched non-cleft individuals. Regression Models for Panel Data assessed how nasal measurements were influenced by surgery, age and gender. Nasal protrusion was equal to non-cleft controls at all ages. Length of the columella was also comparable to controls at 5 and 10 years, but significantly shorter at the end of growth. Inter-alar and nasal tip width and nasolabial angle were significantly wider than controls at all ages: More than 60% of the patients have asked for correction of the nasal width, but no early surgery for columella lengthening was needed. NAM and PCL have provided a nasal projection close to that of non-cleft individuals until adulthood, while length of the columella was physiological at 5 and 10, but shorter than controls at age 20. Width of the nasal tip and width of the alar bases were significantly wider than the controls and eventually required secondary nasal width correction in over two thirds of the sample.

Effect of slide burnishing on the corrosion resistance and surface roughness on high strength steels

This work presents an experimental study aimed to determining the influence of the slide burnishing force on the surface roughness indicators ( Ra, Rz, Rt, Rv, and Rp) and corrosion resistance on the advanced high strength steels TRIP-440Y and DP-330Y and the high strength steel HSLA-SP780. For each steel, the tests were carried out at different burnishing forces between 30 and 450 N, using a zig-zag burnishing toolpath with a 50% of the footprint width of the spherical tip as length between burnishing traces. The results showed that the optimal burnishing force to minimize surface roughness for HSLA-SP780, DP-330Y, and TRIP-440Y steels were 60, 150, and 180 N. These burnishing forces enhanced the roughness indicators between 40.3% and 73.4% for DP-330Y, from 57.5% to 83.2% for TRIP-440Y, and around 2.8% and 41.6% for HSLA-SP780. Corrosion tests exhibited that sliding burnishing does not affect the corrosion resistance of the steels, which are coated with a zinc layer. This result was confirmed by an X-ray diffraction analysis of the burnished samples. The corrosion current for all samples burnished and not burnished with zinc were close to 25 µA. Therefore, slide burnishing technique is an excellent option to improve the surface roughness without affecting the corrosion resistance of these steels, as well as other mechanical and physical properties that have been investigated according to the literature.

Study of the influence of the vessel stern shape on its hydrodynamic characteristics

Determining the main dimensions of the small vessels while designing is an important and difficult task due to the large number of mutually exclusive factors affecting the hydrodynamic characteristics of such vessels. The existing patterns for determining the length, width and draft of small vessels are quite general. This complicates their usage for the vessel of a specific design. In this case, it is necessary to check technical solutions, one of the ways that may be implied is the usage of computational fluid dynamics (CFD) methods. This paper presents the results of the numerical simulation of boat movement in the transient mode with Froude numbers up to 1.2. The process of preparation and numerical modeling of the aerodynamics of a composite wing in the NUMECA/FineMarineTM software package is described, the choice of the turbulence model and the parameters of the computational grid, including the resolution of the boundary layer, is justified. The study of the influence of three variants of the width and shape of the aft tip on the change in draft, trim angle, wetted surface and resistance of the boat is carried out. An increase in the width of the flat planing part of the aft tip has a favorable effect on the hydrodynamic characteristics of a small vessel, even when moving in transition mode at L/B from 3.5 to 3.99. At the same time, the use of the extension of the underwater part of the aft tip requires a more detailed study.

Experimental Study and 3D Optimization of Small-Scale Solar-Powered Radial Turbine Using 3D Printing Technology

Small-Scale Turbines (SSTs) are among the most important energy-extraction-enabling technologies in domestic power production systems. However, owing to centrifugal forces, the high rotating speed of SSTs causes excessive strains in the aerofoil portions of the turbine blades. In this paper, a structural performance analysis is provided by combining Finite Element Methods (FEM) with Computational Fluid Dynamics (CFD). The primary objective was to examine the mechanical stresses of a Small-Scale Radial Turbine (SSRT) constructed utilizing 3D printing technology and a novel plastic material, RGD 525, to construct a SSRT model experimentally. After introducing a suitable turbine aerodynamics model, the turbine assembly and related loads were translated to a structural model. Subsequently, a structural analysis was conducted under various loading situations to determine the influence of different rotational speed values and blade shapes on the stress distribution and displacement. Maximum von Mises and maximum main stresses are significantly affected by both the rotor rotational speed and the working fluid input temperature, according to the findings of this research. The maximum permitted deformation, on the other hand, was more influenced by rotational speed, while the maximum allowable fatigue life was more influenced by rotating speed and fluid intake temperature. Also, the region of the tip shroud in the rotor had greater deflection values of 21% of the blade tip width.

The Low-Loss Spot Size Converter for Alignment with Cleaved Single Mode Fiber

Integrating the graded index (GRIN) waveguide with the 2-D inversely-tapered waveguide, a new design of spot size converter (SSC) has been proposed to couple the light beam between the cleaved single-mode fiber (SMF) and the silicon (Si) wire waveguide on the silicon-on-insulator (SOI) platform. The device demonstrates a low coupling loss of 0.27 dB when it is coupled to a cleaved SMF. The polarization-dependent loss (PDL) is less than 0.25 dB, and the 1-dB alignment tolerance is about −2.0~2.0 µm for both vertical and horizontal directions. At the same time, the starting tip width of the tapered waveguide is kept at the level of the lithography limitation at the current commercial silicon photonics fab. This integrated SSC could be an improved design for reducing the coupling loss between the cleaved SMF and the Si waveguide.

A study on predicting the wear of TBM disc cutters using Cerchar testing

Estimating the disc cutter wear life or change time is a critical part of performance prediction for the application of hard rock TBMs. This paper examines the disc cutter wear rate and the number of required discs during the excavation of the Kanisib (or Zab) tunnel based on the transpositioning concept. The study covers the disc changes due to the normal wear process, leaving out those replaced due to mechanical/bearing failures. This study also analyzes TBM field performance and actual cutter consumption using a method, specific mass loss per volume (SMLV) excavated. SMLV considers the wear mass of a disc cutter relative to the disc cutters replacement for a given volume of excavated rock. Generally speaking, the disc SMLV incorporates critical parameters, and a formula is introduced to calculate it from the rock properties. The new model can be utilized for estimating disc life for any disc cutter size, diameter, and tip width. The predictive model developed in this study allows for estimating cutter life based on the location of disc cutters on the cutterhead. The proposed model uses rock mass parameter, namely the rock quality designation (RQD), and rock material parameters measured in a laboratory, including rock abrasion and strength. Rock abrasion is estimated by Cerchar abrasivity index (CAI) or modified Cerchar abrasivity index (MCAI). Furthermore, a new approach to Cerchar indices has been used, which is based on the pin mass loss instead of pin tip flat size, and as a result, new indices called CAIML and MCAIML are introduced. The correlation between predicted and observed values shows that the proposed model for specific mass loss per volume can predict the normal wear of disc cutters. Furthermore, the Cerchar indices calculated using the pin mass loss offered better correlations with field data than those specified based on the diameter of the pin tip flat. Overall, MCAIML exhibited the best correlation with the field observations compared to the other Cerchar indices.

Changes in Nasal Tip Aesthetics Over Time Following Asian Tip Plasty.

This study aimed to evaluate the sequential postoperative changes in tip aesthetics, by evaluating the aesthetic performance of the septal extension graft with or without tip grafting. A total of 62 patients who underwent rhinoplasty with tip plasty were included. Using a three-dimensional scanner, we measured anthropometric aesthetic features of the nasal tip, including tip height, tip width, nasolabial angle, and columellar lobular angle. Preoperative and 1-month and 12-month postoperative anthropometric parameters were compared. The patients were grouped according to surgical techniques (i.e., septal extension only and septal extension plus tip grafting groups) and subtype of tip graft. The 1-month postoperative values of all four aesthetic features were significantly increased compared with the preoperative values. The tip height, tip width, and nasolabial angle at 12 months were significantly decreased compared with 1 month post-operation values, whereas the tip height and width were still greater than the preoperative values. No difference was found between 1 and 12 month values of columellar lobular angle. There were no differences in the degree of decrease in tip height, tip width, nasolabial angle, and columellar lobular angle between the septal extension graft only and septal extension graft plus tip graft groups. There were no differences in the tip graft by subtypes, single- and multi-layer tip grafts. Increased tip height, tip width, and widened nasolabial angle gained immediately after septal extension grafting surgery gradually decreased over the year regardless of addition of tip graft or tip grafting methods. 4 Laryngoscope, 134:678-683, 2024.

Electroporation effect of ZnO nanoarrays under low voltage for water disinfection

Abstract It is quite necessary to develop a safe and efficient technique for disinfection of drinking water to avoid waterborne pathogens of infectious diseases. Herein, ZnO nanoarray electrodes with different sizes were investigated for low-voltage and high-efficiency electroporation disinfection. The results indicated that the ZnO nano-pyramid with small tip width and proper length exhibited over 99.9% disinfection efficiency against Escherichia coli under 1 V and a flow rate of 10 mL/min (contact time of 1.2 s). The suitable size of the nanoarray for electroporation disinfection was optimized by establishing the correlation between four kinds of ZnO nanoarrays and their efficiency of electroporation disinfection, which can guide the preparation of next-generation electroporation-disinfecting electrodes.

Rock cutting performance and wear characteristics of undercutting disc cutter: Based on experiment and DEM

The undercutting disc cutter used to break the hard rock bears a huge load and severe wear during rock fragmentation; however, the wear mechanism and law of the cutter are still unclear. The wear mechanism of the undercutting disc cutter was revealed by comparing and analyzing the three-dimensional topography of the cutter before and after the experiments. Based on the DEM, the numerical model of rock cutting using an undercutting disc cutter was established and the influence of factors such as structural and working parameters on the wear behavior of the cutter was studied. The results indicate that under the large contact force, the hard particles of rock are inset into the cutter tip and the material was spalled, resulting in the local pits; the furrows on the cutter face are not continuous and less deep because of the contact between the cutter face and the bottom rock free-face is discontinuous. The wear of the cutter is positively related to the cutting depth and tip width, and negatively to the cutting angle. The circular tip has better wear resistance than the flat tip, and the effect of the tip angle on the wear of the cutter is not significant. The index of cutter consumption ratio (CCR) is proposed, and combined with the specific energy, the recommended structural and working parameters of the cutter for improving the cutting performance and reducing cutter wear are provided.

A COMPARATIVE STUDY ON THE QUALITY OF HONEY BEE (Apis mellifera) QUEENS DEVELOPED FROM LARVAE AFTER THE COLLECTION OF ROYAL JELLY

Rearing bee queens is almost done utilizing grafting young larvae while the effects of grafting using old larvae after the collection of royal jelly on the quality of queens are not known. In fact, the production of royal jelly depends on grafting, then discarding the larvae to collect the royal jelly. This study aimed to investigate this point by grafting old larvae after removing them from their original cells without food. Larvae at age about 2 days were grafted into plastic queen cell cups (selection and grafting method or S&amp;G method) leaving royal jelly behind and then resultant queens were compared with naturally reared ones (or NQ). The study showed the absence of significant variations between the queens reared from the two methods in characteristics of queens and cells. Meanwhile, no significant differences were found in regard to the performance of colonies. The colonies with queens from S&amp;G method had slightly higher performance than those with NQ. The study concluded that grafting using old larvae without their original food does not impair the quality of queens. During the production of royal jelly, larvae may be grafted into new cells to continue their normal development instead of discarding them.