---

During the study of aphid fauna of North-Khorasan province, Iran, an aphid species, Brachycaudus cerasicola (Mordvilko, 1929) (Hem.: Aphididae), was collected on Salvia aethiopis, Stachys turcomanica, Hymenocrater elegans, Perovskia abrotanoides and Phlomis cancellata (Lamiaceae) in 2016 and 2017 which is reported here for the first time from Iran. The first to third host plants reported as the new hosts for this aphid. Since the original descriptions of this species by Mordvilko (1929) and Shaposhnikov (1964) are rether brief, so we report here additional notes and more detailed biometric data on this species. The biometric data of the Iranian populations of B. cerasicola is given and compared to the original descriptions.

---

Research subject: Polymer nanofibers have attracted much industrial interest over the past decade. In general, these fibers are suitable for a variety of applications including medical applications, insulation, capacitors, advanced aerospace technologies, and so on. Specifically in aerospace technology, the used materials must be thermally stable with suitable electrical conductivity. However, many of these polymer nanofibers suffer from low temperature degradation and low electrical conductivity, limiting their use in many potential applications. Graphite has unique properties such as high conductivity and high thermal stability. This exceptional material can be included as a nanoparticle in polymer nanofibers to modify electrical and thermal properties.The aim of this research was to investigate the effect of addition of graphite nanoparticle on thermal and electrical propertiesof polymer fibers.
Research approach:  For this purpose, polyvinyl alcohol 72000 (PVA) as a non-conductive polymer and graphite nanoparticles were used. Polyvinyl alcohol-graphite nanofibers were synthesized method by electrospinning technique under optimized parameters. The optimum conditions for the electrospinning process were: PVA concentration of 8%, applied voltage of 22 Kv, flow rate of 10 ml and tip/collector distance of 20 cm.
Main results:  Scanning electron microscopy (SEM) studies showed that produced PVA fibers were smooth, continuous without any bead, with a diameter of about 350 nm. The PVA / graphite nanofibers were also smooth but much thinner (about 200 nm) than PVA fibers at the same processing parameters. Moreover, X-ray patterns of PVA/graphite nanofibers include peaks of graphite particles in the structure and slso the suppression of crystallinity.  According to the results of 4 point probe teste, by increasing weight percentage of graphite in the fibers, electrical conductivity increased up to 0.5 . The thermal behavior of PVA nanofibers after mixing with graphite was also investigated by differential calorimetry analysis (DSC) and TGA. It was demonstrated that PVA / graphite nanofibers are thermally stable up to 300 ° C.

---

The effect of temperature on demographic parameters of the greater wax moth, Galleria mellonella (L.) was studied at 23, 25, 27, and 30 °C, 50 ± 10% RH and a photoperiod of 16:8 (L: D) h. The life table parameters were estimated according to the age-stage, two-sex life table procedure. In addition, the bootstrap technique was employed for estimating the means, variances, and standard errors of the population parameters at all studied temperatures. All estimated parameters were affected considerably by temperature. Among examined temperatures, the highest values of net reproductive rate (R₀), intrinsic rate of increase (r_m) and finite rate of increase (λ) were 223.04 egg, 0.096 day^-1, and 1.101day^-1, respectively at 27 °C. The lowest mean generation time was 50.31 day at 30 °C. Moreover, the highest reproductive value was observed at 27 °C. According to the results, temperature can affect all life table parameters of G. mellonella, and according to our investigation, 27 °C is the best temperature for its mass rearing in laboratory condition among the evaluated temperatures.

---

During 2015–2017, 28 aphid species belonging to 12 genera were collected and identified on Asteraceae plants in North Khorasan province, Iran. Among these, three aphid species including Macrosiphoniella frigidivora Holman & Szelegiewicz, 1974, Macrosiphoniella szalaymarzsoi Szelegiewicz, 1978 and Protaphis iliensis Kadyrbekov, 2001 (Hemiptera: Aphididae) are new for aphid fauna of Iran. Brief redescriptions of Iranian populations of these three species are given and compared to the original descriptions.

---

Research Subject: The conversion of carbon dioxide into hydrocarbons is a potential process that can reduce and control greenhouse gases. According to the United Nations Development Program's sustainable development goals, liquefied gas is an environmentally friendly fuel. Hydrogenation of carbon dioxide over a suitable catalyst can be used directly to synthesize light hydrocarbons.
Research Approach: This study investigated the direct synthesis of liquefied petroleum gas from carbon dioxide hydrogenation using SBA-15 catalyst modified with copper and zinc nanoparticles. In this study, hydrogen and carbon dioxide were used as reactant gases, and the operation conditions such as reaction temperature and residence time were evaluated.
Main Results: The results showed that by modifying the catalyst with copper and zinc active sites, the active surface of the catalyst was reduced to 542 m².g^-1. Furthermore, SEM results revealed that the addition of metal oxides ZnO and CuO resulted in uniform distribution in the internal channels of the 1Cu1Zn/SBA-15 catalyst, with no aggregation. LPG production is optimal at a temperature of 360 ^oC and a residence time of 10 g.h.mol-1. These conditions yielded a CO₂ conversion rate of 24.6% and a LPG selectivity of 64.8%, respectively. The amount of LPG produced increases as the temperature rises, and after reaching the optimum temperature, there is no significant increase in the amount of LPG produced. The percentage of CO2 conversion does not change much when the residence time is increased after the optimum value, indicating that the reaction has reached its thermodynamic theoretical range. According to the catalytic lifetime test of 1Cu1Zn/SBA-15, CO₂ conversion percentage and LPG selectivity do not change after 85 hours. Based on the results of the experiments, the synthesized catalyst can hydrogenate CO₂ efficiently to LPG.
 

---

Learning strategies are amongst the tools that learners use to learn languages. In other words, learning strategies are widely introduced as techniques or methods that students often use to improve their learning skills in second language. Despite the importance of strategies and their role in accelerating and effective learning, few researches have been conducted on the impact of strategies on the success of learners in learning language skills. Also no reliable research has been done so far to study the effect of strategies on the success of non-Iranian Persian speakers. Therefore, due to the impact of using strategies on learning language skills, this study examines the impact of memory, cognitive and compensation strategies on the success of Persian language learners in writing skill. To this end, the following questions were raised:

1. Is there a significant relationship between using memory strategies and the success of non-Iranian Arabic language learners in writing skills?
2. Is there a significant relationship between using cognitive strategies and the success of non-Iranian Arabic learners in writing skills?
3. Is there a significant relationship between using compensation strategies and the success of non-Iranian Arabic learners in writing skills?
4. Is there a relation between applying total direct strategies (cognitive and compensation strategies) and the success of non-Iranian Arabic learners in writing skills?
5. Is the contribution of using each of the direct strategies the same in predicting the success of non-Iranian Arabic-speaking learners in writing skills?

According to the above questions, the following hypotheses are considered:

• Hypothesis 1: There is a significant relationship between using memory strategies and the success of non-Iranian Arabic language learners in writing skills.
• Hypothesis 2: There is a significant relationship between using cognitive strategies and the success of non-Iranian Arabic language learners in writing skills.
• Hypothesis 3: There is a significant relationship between using compensation strategies and the success of non-Iranian Arabic language learners in writing skills.
• Hypothesis 4: There is a relation between applying total direct strategies (cognitive   compensation strategies) and the success of non-Iranian Arabic learners in writing skills.
• Hypothesis 5: The contribution of using each of the direct strategies is different in predicting the success of non-Iranian Arabic-speaking learners in writing skills.

The sample of this study consists of 42 non-Iranian Arabic-speaking Persian learners (men and women) who were in age range of 18-20 years old. These learners were learning Persian language in advanced level in the fall semester 2016. Oxford Language Learning Strategies Questionnaire (1990) is used to measure application of strategies, and the students' scores in the course of writing were used to determine the relationship between language learning strategies use and Persian learners' success in writing skill. The analysis of the hypotheses was done using Kolmogorov-Smirnov test, Pearson correlation coefficient and regression and the results of the Pearson correlation coefficient test showed that there is a significant positive relationship between the use of memory strategies with success in writing skill. In addition, according to the results of correlation coefficient, there is also a significant positive correlation between the use of compensation strategy and success in writing skills. This is despite the fact that according to the findings, there is not a significant relationship between the use of cognitive strategies and learners success in writing.  Regression analysis also indicated that among direct learning strategies, two types of memory and compensation strategies, causes success of Persian learners in is writing skill. And among these strategies, compensation strategies are more effective than memory strategies on success of Persian learners. Finally suggestions for teaching strategies in the classroom were presented.
 

 

---

---

---

Residual stress measurement is one of the most interesting research areas in experimental mechanics. Residual stress is introduced to material due to plastic deformation of parts and can be one of the most effective parameters on design and operation of parts. ASTM E837-01 standard studies residual stress determination in parts by hole drilling method and represent calibration coefficients for flat sheets with constant stress profile. However, there is no certain standard on the residual stress measurement by Incremental Hole Drilling Method (IHDM) which is the subject of this study. IHDM can obtain stress profile by using two modified stress calibration coefficients. In this article, the stress calibration coefficients have been extracted for incremental hole drilling by using finite element analysis (FEA). FEA contains both biaxial tension test and pure shear test which a hole has been drilled step by step in the parts by removing elements and the strains changes were determined at three strain gauge positions on the surface. At last, the calibration coefficients are determined for each step and the accuracy of coefficients have been verified by a set of experimental test and a FE analysis. The experimental test contains four-point bending of an AA5056 flat aluminum sheet. The numerical analysis contains four-point bending of a flat sheet. In both cases, the stress profile can be determined easily by using analytical equations. Average analytical stress in each increment has been calculated and compared with the result of numerical incremental hole drilling method. The comparisons show that numerical and experimental results have no significant differences in first six steps but in the last four steps show an increasing errors due to the change in stress profile and hole geometry. Results presents that the calibration coefficients have suitable accuracy in stress profile determination.

---

Breast cancer is a serious health concern for women. It contributes to about 23% of the cancer cases, and accounts for the second largest number of deaths among all cancers. Expensive and time consuming recognition methods currently available for recognition of breast cancer potentiates the need for improvement of novel, specific and ultrasensitive strategies. Biosensors are sensitive, specific and cost effective procedures. These also display the benefit of quick response due to direct calculation in physiological fluids (saliva, blood, serum, milk, urine etc.) in a non-invasive way. Aptamer-based biosensors for cancer cell recognition have shown advantages of rapidness, simplicity and cost-efficiency over traditional approaches. In this study, by linking DNAzyme and aptamer together, we established colorimetric biosensor for the detection of MCF7 breast cancer cells.  MUC1 and PTK7 aptamers used as specific aptamers to binding to the breast cancer cells. This manner may also evade the modification of DNA and the use of labels, which can intensely rise the cost-efficiency and simplicity of cancer cell discovery. Our results indicated that these aptamers showed good activity for breast cancer cells detection in which in the control cells no activity was observed. Results also indicated that there is a good linear relationship between the cancer cell values and colorimetric signal. Finally, the obtained results indicated a cost effective and conveniently operated approach for cancer diagnosis in future.

---

In the present paper, the parameters of Johnson - Cook (JC) constitutive model for two steels have been identified, based on the Hopkinson pressure bar test results. The experimental data has been taken from the split Hopkinson pressure bar data found in the literature. Using the measured strain pulses, the experimental stress - strain and deformation - time curves can be extracted. The experimental data have been processed using two different methods. In the first method strain rate assume to be constant during deformation and in the other one the deformation has been applied to a modeled specimen. In each method, an optimal set of material constants for JC constitutive model have been computed by minimizing the standard deviation of the numerically obtained stress - strain curve from the experimental data. Also a sensitivity analysis has been performed on JC constitutive model parameters and temperature changes during test have been investigated. The obtained results show that using constant strain rate method, leads to considerable error in results; for example in this study the minimum error is about 14%.

---

In present paper the Inamuro Model based on free energy approach of the Lattice Boltzmann Method (LBM) was used to simulate the motion of bubble and coalescence of two bubbles under buoyancy force. By combining the Tanaka and Inamuro models, three-dimensional model of Inamuro was used in two-dimension for decreasing the computational cost. Firstly it was ensured that the surface tension effect and Laplace low for two density ratio 50 and 1000 were properly implemented. Secondly in next step, effect of governing dimensionless numbers problem such as Etvos number and Morton number on Reynolds number and terminal shape of bubble were investigated. Different flow patterns in various dimensionless numbers were obtained and by changing the dimensionless number, terminal change of bubble’s shape was seen. Finally, motion of two bubbles and terminal shape of coalescence of two bubbles were studied in different dimensionless number, which shape of first bubble was same to single bubble, but it was seen that second bubble experienced various shapes due to its location in wake of first bubble and less difference pressure on two sides of this bubble.

---

New trends have been observed in recent years for rapid prototyping of sheet metal parts by Incremental Forming process particularly at low quantity production. Recent ideas have been presented for a new type of this process known as Incremental sheet metal hammering (ISMH) method. In ISMH process, by sequence moving of a hammering punch over a clamped sheet metal, a three-dimensional work piece is produced without using a die. In this paper, the effect of tool parameter on the formability of Al-1100 will be studied. To investigate this issue, the sheet is clamped. Then by considering the cone angle, hammering is applied at a certain diameter and frequency until the failure happens. By recording the angle and the height values at failure point, a correlation has been extracted between the diameter and the frequency. Analysis of the results shows that by decreasing the diameter of the punch, maximum strain in the direction of thickness is observed at higher height. Also, by increasing the diameter of the punch, formability of Al-1100 increases. Also, it is shown that by increasing the impact frequency, the formability of the sheet will be decreased.

---

A novel geometrically nonlinear high order sandwich panel theory considering finite strains of sandwich components is presented in this paper. The equations are derived based on high order sandwich panel theory in which the Green strain and the second Piola-Kirchhoff stress tensor are used. The model uses Timoshenko beam theory assumptions for behavior of the composite face sheets. The core is modeled as a two dimensional linear elastic continuum that possessing shear and vertical normal and also in-plane rigidities. Nonlinear equations for a simply supported sandwich beam are derived using Ritz method in conjunction with minimum potential energy principle. After obtaining nonlinear results based on this enhanced model, simplification was applied to derive the linear model in which kinematic relations for face sheets and core reduced based on small displacement theory assumptions. A parametric study is done to illustrate the effect of geometrical parameters on difference between results of linear and nonlinear models. Also, to verify the analytical predictions some three point bending tests were carried out on sandwich beams with glass/epoxy face sheets and Nomex cores. In all cases good agreement is achieved between the nonlinear analytical predictions and experimental results.

---

In this research the designed mechanism for chasing and repoussé of sheet metal is studied. This mechanism is similar to incremental sheet metal forming. In this kind of sheet metal forming, sheet is fixed and forming tool pastes desired pattern incrementally. The major difference between designed mechanism and traditional incremental forming is as follows: control on the punch energy and sequence, and fixing sheet by using protectant material behind it instead of clamping sheet sides. In this mechanism, the solenoid is used as a hammer. The plunger moves to the center of the coil while energized. Striking energy could be controlled by controlling the excitement voltage and punching sequence thus could be adjusted by manipulating the excitement algorithm. In this paper, the utilized solenoid is simulated. The mechanical and magnetic relations are merged for this. And the effect of core head geometry and plunger mass and coil covers on the strike energy and hence power is studied.

---

In this study the delamination behavior of FMLs loaded under mode I and II conditions is investigated by using numerical modeling and acoustic emission (AE) data analysis. Test samples is made of prepreg (glass/epoxy composite) and aluminum 2024-T3 (chromic acid anodized). Detection of delamination initiation moment is required for calculation of interlaminar fracture toughness in mode I and II which this moment is detected by using AE technic. Initiation and propagation of delamination is modeled by Abaqus software by using cohesive element. Load-displacement curve, progressive debonding and delamination face are the results taken from FEM and are compared with test results. Signal frequency processing is done for identifying delamination propagation and classification of fracture mechanism. Delamination mechanism is validated by Scanning electron microscope (SEM) images.

---

The equations of Lamb wave propagation in an infinite isotropic micro plate with finite thickness on the basis of consistent coupled stress theory is presented in this study. By employing the characteristic length scale parameter, the effect of micro-plate size is considered, and thereby the effects of different plate dimensions on the dispersion of Lamb waves is illustrated. Lamb wave propagation velocity in aluminum nitride micro-plates has received many interests due to its applications in surface acoustic resonators. In the current work, at first, the dimensionless relations are developed through the definition of dimensionless parameters where the extracted curves can be applied to all thicknesses, propagation wavelengths and characteristic length scale parameters of a micro-plate. In addition, using the quasi-static approximation, the Lamb wave dispersion curves in both symmetric and asymmetric modes for an aluminum nitride micro plate are plotted and compared with the results from the classical theory. The integrity of the present formulation is verified by comparing the obtained results with the experimental data in the literature. Finally, by employing the dispersion curves and the reported experimental data, a novel method has been proposed to determine the size of characteristic length parameter in the consistent coupled stress theory.

---

In this paper, acoustic emission monitoring of repaired aluminum 2024-T3 sheet with FML patch is studied. For the experimental investigation, 12 samples were made and classified into 4 categories according to the crack angle (zero and 45 degrees), and repaired or unrepaired state. To reduce manufacturing errors, composite prepreg is used for producing patches, aluminum surfaces is anodized and curing is done in an autoclave. In fatigue crack initiation process by using Acoustic Emission data acquisition, crack initiation moment is detected. By using Acoustic Emission signal cumulative energy parameter onset of delamination, growth of delamination and critical delamination growth is identified. SEM image and investigation of failure surface are used for detecting of failure mechanism. By introducing one frequency analysis method tried to classify frequency range of failure mechanism signals. Because of frequency range intersection of matrix cracking, fiber/matrix separation and delamination of patch from aluminum sheet, force-displacement curve is divided to 3 zone and frequency analysis is done in each zone that occurrence possibility of certain failure mechanism is higher than the others. Signal frequency range of aluminum plasticity and crack growth is in the range of 440-480 kHz, and signal frequency range of delamination is in the range of 100-150 kHz and 200-220 kHz.

---

In this paper, the nonlinear free vibrations of a bimorph piezoelectric nanoactuator is studied based on nonlocal elasticity. The Euler-Bernoulli beam theory and Hamilton’s principle are used to derive the equation of motion of the actuator. In order to obtain the reduced-order form of equations, the Galerkin method is used. The mode shapes of a multi-span beam are used for a faster convergence. The nonlinear natural frequencies are obtained by using He’s variational approach. Equations are solved for clamped-clamped boundary conditions, and the effects of values of DC voltage, actuator length and thickness, length of piezoelectric layers and nonlocal parameter on the nonlinear natural frequencies are studied. The results show that applying a DC voltage induces a static deflection and an increase in the stiffness of the actuator. Therefore, the natural frequency increases. Moreover, increasing the nonlocal parameter decreases the rate of change in frequency variation. An increase in the nonlocal parameter or the length of the actuator increases the nonlinear to nonlinear natural frequency ratio. Finally, the effect of the middle layer material of the actuator on the frequency ratio is studied.

---

The destruction of the bridges because of the erosion of the bed is a question that if is not addressed properly it can’t be compensated. The aim of this research reviews the scour around the twin bridge piers affected by parameter of time and its role in the bed topography. In this research, the equilibrium time test was done to determine the equilibrium time. After that a test without the establishment of bridge pier was done. The aim of this test is to know the effect of steep bend flume to the bed topography and scour pattern. The next tests were done at 20, 50 and 100 percent of the relative equilibrium time with the establishment of the twin bridge piers. The experiments were performed at the Advance Hydraulic Laboratory of Persian Gulf University of Bushehr in Iran. The channel used in this study has 1 m wide and bend routh with the 180 degrees angle flume with the relative curvature of 2. The upstream routh has the length of 6.5 m and the downstream path is 5 m long. The condition was clear water in all test and live bed using sediment with average diameter of 1 millimeter and standard deviation equals to 1.3. Flow rate was fixed at 70 litter per second with depth of 18 centimeter at straight upstream rought. The piers had the diameter of 5 centimeter and making the angle of 21 degrees with the vertical axis and also placed at the perpendicular plane to the flow stream. Due to maximum scouring at 60 degree of the flume in preliminary tests without the establishment of the piers, for the rest of the tests the piers were installed at 60 degrees angle of the channel bend. At the end of each test channel was gradually drained and after drying the bed topography was harvested with the use of laser device called bed topographer with the accuracy of 1 millimeter. For the best result according to the test more than 4500 points were measured. The most important results achieved is that by the relative equilibrium time the second scour hole is 12 percent deeper than the main scour hole around the piers. In addition the second scour hole is created at the 123 degrees along the outer wall of the flume. Studying the parameter of time indicated that at the beginning of the experiment the second pier which is closer to the outer wall has more scouring depth , but after the relative balance time of 20 percent both pier has the same scouring rate. Reducing the time of the test by 100% to 50% of the relative equilibrium time reduces the maximum scouring depth of the main hole by 20 percent. In all test a scour hole at the middle of the channel bend was seen which deeper at 50 percent of the equilibrium time compared to the 100 and 20 percent of the relative equilibrium time. Advanced discussion and analysis about the results achieved from the tips are outlined in this paper