Abstract: Determination of **optimal** **tilt** **angle** for seasonally adjusted flat-plate photovoltaic (PV) modules based on Perez transposition model is presented. Particularly, two seasons are considered, namely winter and summer. As such, two **optimal** **tilt** angles are obtained which requires that the **tilt** **angle** the of flat plate PV module will be adjusted twice in a year. The method is based on yearly global radiation incident on a horizontal plane as downloaded from NASA website. Furthermore, PVSyst software that uses transposition model is used to generate the yearly global radiation incident on a tilted plane for various **tilt** angles, from 0° to 46°. The location used in the study is at longitude of 7.860761, latitude of 5.011474 and elevation of 67.506 m. The results show that the winter season **optimal** **tilt** **angle** is 25.46° the summer season **optimal** **tilt** **angle** is 0° and the yearly fixed **optimal** **tilt** **angle** is 7.16°. The annual transposition factor for the seasonally adjusted **tilt** **angle** is 1.05 whereas annual transposition factor for the year fixed **tilt** **angle** 1.01 . The result amounts to 3.6% improvement is solar radiation capture due to the seasonal adjustment of the **tilt** **angle** when compare to the yearly fixed **tilt** **angle**.

Abstract: In this paper, a method for the determination of the **optimal** **tilt** **angle** for yearly fixed flat-plate photovoltaic (PV) module at any given location is presented. The method is based on yearly global radiation incident on a horizontal plane as downloaded from NASA website. Futrthermore, PVSyst software that uses transposition model is used to generate the yearly global radiation incident on a tilted plane for various **tilt** angles, from 0° to 46°. The study is conducted for a health facility in Uyo, Akwa Ibom state, Nigeria with longitude of 7.860761, latitude of 5.011474 and elevation of 67.506 m. The **optimal** **tilt** **angle** is obtained from the quadratic trendline equation fitted to the graph of the transposition factor versus **tilt** **angle**. The result is that the **optimal** **tilt** **angle** for the yearly fixed flat-plate PV module at the selected Flocation is 9.71 ° which gives average yearly transposition factor 1.0105. Essential, the results indicate that about additional 1.05% of solar radiation will be captured per year by tilting the PV module at **optimal** **tilt** **angle** of 9.71 ° . At any other **tilt** **angle** less solar radiation will be captured per year.

PV. While having maximized incident solar radiation, we require **optimal** **tilt** inclination of PV module [6]. Photovoltaic (PV) panels convert solar energy into electrical energy with the peak efficiencies in the range of 5–20%, depending on the type of PV cells [7]. The National Action Plan on Climate Change (NAPCC) is the main key plan for the development of solar energy technologies in India. The Government of India approved “Jawaharlal Nehru National Solar Mission” (JNNSM), in November 2009. The Mission mainly focuses on deployment and development of solar energy technologies in the country to achieve parity with grid power tariff by 2022 [8]. On the optimum **tilt** **angle** of the solar system, several studies have come into the field of vision in the literature. Milan Despotovic and Vladimir Nedic [9] examined the optimum **tilt** **angle** of solar collectors for Belgrade, which is situated at the latitude of 44ᵒ47’N. They found yearly, biannual, seasonal, monthly, fortnightly, and daily optimum **tilt** angles by looking for the values for which the solar radiation on the collector surface is maximized. They observed that, by installing the PV panels at yearly, seasonal and monthly optimum **tilt** angles, yield increases amount of collected solar energy by a factor of 5.98%, 13.55%, and 15.42% respectively compared to PV panels at current roofs’ surface angles. Hamid Moghadam and Saeed Moghadam Deymeh [10] determined the optimum location and optimum **tilt** **angle** of solar collectors placed on the roof, in respect of the shadow of adjacent buildings. Their result suggests that for northern hemisphere of the earth solar collectors should be installed on the southern verge of the roof as far as possible away from the bigger adjacent building. They found that optimum location direct solar radiation collected energy could be increased furthermore the 15%. In addition to this, shade has little effects on the optimum **tilt** **angle** for the parts of the roof near to the taller adjacent building.

An **optimal** **tilt** **angle** essentially can be calculated by using MATLAB which provides quick and correct results. When the necessary inputs are provided to the matlab code, gives out the respective **tilt** to the relevant data at location of interest. This saves lot of time and complex math calculations which are to be done manually otherwise. Also this code provides greater flexibility in finding optimum **tilt** instantly for any number of sites by simply changing the inputs and executing the code. The code with comments given below is easy to

Number of previously published researches within optimization solar **tilt** **angle** and estimation solar radiation which are shown as follows. M. Benghanem, 2011, investigated the optimum choice of the **tilt** **angle** for the solar cells in order to collect the maximum solar insolation in Saudi Arabia depending on the measured values of daily diffuse and global solar radiation on a horizontal plane [4]. K. Bakirci, 2012, dealt with finding the optimum **tilt** **angle** of solar panels for solar energy systems using solar radiation data measured for eight big provinces in Turkey [5]. D. Lahjouji and H. Darhmaoui, 2013, examined the theoretical features that calculate the optimum **tilt** **angle** and makes recommendations on how to rise the solar energy collected by changing the **tilt** **angle** depending on the values of daily global radiation on a horizontal plane (from NASA) in Ifrane, Morocco [6]. T. Khatib, et al., 2015, presented an approach for optimizing the **tilt** **angle** of solar arrays installed in the five locations in Malaysia based on manually varying in **tilt** **angle** for maximum power generation [7]. A. K. Yadav and H. Malik, 2015, calculated the **optimal** **tilt** **angle** for six locations in India based on correlation in terms declination **angle** [8]. T. O. Kaddoura, et al., 2016, investigated optimum **tilt** angles of PV panels for different cities in the Saudi Arabia. Solar radiation data of horizontal surface for the study cities was obtained from NASA and MATLAB software was used in order to improve **tilt** **angle** [9]. N. Ihaddadence, et al., 2017, aimed to find the best inclination **angle** of fixed solar conversion systems in M'Sila region experimentally and theoretically (using empirical method) based on data taken from NASA Climatology resource for solar radiation on a horizontal surface [10]. A. A. Abbood, et al., 2017, suggested implementing energy management techniques using solar cells for residential sector in Baghdad city. The estimation of solar radiation data and PV system design has been simulated based on MATLAB software. The proposed **tilt** angles have been changed and optimized manually and based on conclusion for researchers [11]. Y. Lva, et al., 2018, an optimized mathematical model is proposed and used to calculate the **optimal** **tilt** **angle** and orientation of solar collectors set up in Lhasa during the summer season [12].

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the **angle** of PV arrays with respect to horizontal, is a dominant parameter affecting the collectible radiation of a fixed PV array. In general, the **optimal** **tilt** **angle** of a fixed PV array is related to the local climatic condition, geographic latitude and the period of its use. Hence, different places will have different **optimal** **tilt** angles for a yearly-used solar PV array. To date, a number of studies on the **optimal** **tilt** **angle** of PV arrays have been conducted [1–8], and a lot of empirical correlations for estimating the **optimal** **tilt**-**angle** are available in the literature [2, 5–8]. It is reported in the literature that the optimum orientation of the PV array should be directly towards the equator, facing south in the northern hemisphere and the optimum **tilt** **angle** depends only on the latitude. For example, Lunde [8] and Garge [9] β opt = ± 15 ° , Duffie and Beckman [10] suggested

The performance of a solar collector is highly dependent on its **tilt** **angle** with the horizon. The variation of **tilt** **angle** changes the amount of solar radiation reaching the collector surface. Meanwhile, is the rule of thumb, which says that solar collector should be orientated towards the Equator with a **tilt** equal to latitude, is valid for high latitud es region? Thus, it is required to determine the optimum **tilt** for Equator facing collectors. In addition, the question that may arise: how many times is reasonable for adjusting collector **tilt** **angle** for Equator facing collectors? A mathematical model was used for estimating the solar radiation on a tilted surface, and to determine the optimum **tilt** **angle** and orientation (surface azimuth **angle**) for the solar collector at any latitude. This model was applied for determining optimum **tilt** **angle** in the high latitudes zone in the Southern and Northern Hemispheres, on a daily basis, as well as for a specific period. The optimum **angle** was computed by searching for the values for which the radiation on the collector surface is a maximum for a particular day or a specific period. The solar radiation on the collector surface of optimum **tilt** **angle**, of latitude **tilt** **angle** and of null **tilt** **angle** was calculated for a particular day or a specific period. The results reveal th at changing the **tilt** **angle** 12 times in a year (i.e. using the monthly optimum **tilt** **angle**) maintains approximately the total amount of solar radiation near the maximum value that is found by changing the **tilt** **angle** daily to its optimum value. This achieves a yearly gain in solar radiation up to several times of the case of a horizontal surface depending on the latitude value.

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electron microscopy study (HRTEM) has revealed that the grain boundary was free from any secondary phases, and the two single crystals contact each other perfectly at an atomic scale. The boundary shows almost straight feature without any step structures whereas a part of the boundary forms facet structures consisting of low index planes such as {310} and {110}. On the other hand, it was found that the contrasts due to strong strain ﬁelds existed on the grain boundary plane with a spacing of 7.6 nm by weak beam dark ﬁeld observation. Comparing with atomic structural analysis using HRTEM, the strain ﬁeld results from a distorted 13 unit structure, which can be predicted from a rigid body model of 13 relation. This distorted unit structure has a similar structure of 17 relation. Namely, the boundary consists of a periodical array consisting mainly of 13 unit structures and partially 17-like unit structures. In other words, a misﬁt **angle** in this boundary was accommodated by not introducing secondary dislocations, but a transformation of basal unit structure.

The motion analysis system was calibrated before each gait analysis. Participants were simultaneously videotaped from the front and side, and measurements were recorded in the sa- gittal, coronal, and transverse planes. Kinematic data included the **angle** of pelvic **tilt**, pelvic obliquity, pelvic rotation, hip flex- ion and extension, hip adduction and abduction, hip internal and external rotation, knee flexion and extension, ankle plan- tar and dorsiflexion, and foot internal and external rotation. All kinematic and temporospatial data were processed and plot- ted, and the graphs were visualized using Polygon software ver. 3.5.1 (Oxford Metrics Inc., Oxford, UK), which was inter- worked with a three-dimensional motion analysis system. To perform the statistical analysis, three points from each joint range of motion from continuous raw data in the lower extrem- ity were used: initial contact (the moment when the heel struck the floor), the minimal joint **angle**, and the maximal joint an- gle during the whole gait cycle. 22

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Measurement show a behavior of resonant refractive index with a strong reflection of the wave at the resonance (Figure 3). This resonance occurs for a certain **angle** between the polarization of the wave and the particle’s main axis, defined as phi in this paper, which is shown on Figure 4, where stands the transmission parameter with respect to that **angle**.

There are some limitations of this study. First, the knee flexion **angle** could not be controlled for a retro- spective study. Therefore, the difference in the **angle** in each pair of images was not same. Second, the 3-mm slice thickness may negatively affect measurement accur- acy. Third, some commonly used parameters, such as the tibial tubercle–trochlear groove distance and the varus–valgus **angle**, were not assessed in this study. Fi- nally, further stratification based on age, sex, BMI, and diagnosis was not undertaken because of the small sam- ple size.

working at a **tilt** **angle** of 20° decreased the power of the cell by 41% after 30 working days while the use of angles of 40° and 60° caused a decrease of 11% and 21% Respectively. Here, we should point out that the month of December in Baghdad is one of the least dusty months; because of rains sometimes occur during this month. In this case, the impact of dust will be greater in months like April or June where the dust storms are almost daily.

Abstract. Most vision control of the existing power-line insulator robot system needs to be realized indirectly through the remote computer. The vision system itself does not have the ability of vision control, and the level of automation is low. In order to improve the visual control ability and automation level of the power-line insulator robot, an on-line spatial control parameter acquisition algorithm for insulator is presented based on target extraction. The algorithm can be embedded in the hardware platform of visual system to automatically measure **tilt** **angle** of insulators. The results of hardware implementation show that the proposed algorithm can measure **tilt** **angle** parameters relatively accurately on the hardware platform of visual system. The error of **tilt** **angle** measurement is 0.4°~4°, which achieves the desired effect and design requirements.

Sunspot groups and bipolar magnetic regions (BMRs) serve as an observational diagnostic of the solar cycle. We use Debrecen Photohelographic Data (DPD) from 1974–2014 that determined sunspot **tilt** angles from daily white light observations, and data provided by Li & Ulrich that determined sunspot magnetic **tilt** **angle** using Mount Wilson magnetograms from 1974–2012. The magnetograms allowed for BMR **tilt** angles that were anti-Hale in configuration, so **tilt** values ranged from 0 to 360 ◦ rather than the more common ± 90 ◦ . We explore the visual representation of magnetic **tilt** angles on a traditional butterfly diagram by plotting the mean area-weighted latitude of umbral activity in each bipolar sunspot group, including **tilt** information. The large scatter of **tilt** angles over the course of a single cycle and hemisphere prevents Joy’s law from being visually identified in the **tilt**–butterfly diagram without further binning. The average latitude of anti-Hale regions does not differ from the average latitude of all regions in both hemispheres. The distribution of anti-Hale sunspot **tilt** angles are broadly distributed between 0 and 360 ◦ with a weak preference for east–west alignment 180 ◦ from their expected Joy’s law **angle**. The anti-Hale sunspots display a log-normal size distribution similar to that of all sunspots, indicating no preferred size for anti- Hale sunspots. We report that 8.4% ± 0.8% of all bipolar sunspot regions are misclassified as Hale in traditional catalogs. This percentage is slightly higher for groups within 5 ◦ of the equator due to the misalignment of the magnetic and heliographic equators.

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The results in both simulation and experiment show that, except that the errors in the vertical translations are under 1.5%, all of the other errors are around 10%. The reason might be that there is no restriction on the directions of displacement with a single-axis amplifier, whereas with the six-axis stages, the vertical, horizon and rotational displacements altogether need to keep the top plate horizontal, the **tilt** displacements need to make the top plate **tilt** symmetrically and no interference from the six amplifiers is allowed with one another. All these cause restriction onto the amplification and, therefore, make it hard to reach the expected range. However, when applied to manufacturing in the future, a linear scale will be built into this mechanism, and the errors in displacements can be better controlled so as to promote its precision.

This study showed the relationship between the rotation **angle** of the middle trunk during trunk bending and that at TO of the affected side while walking. At TO, the trunk is placed in front of the affected foot, and the affected hip joint starts to flex toward the swing phase from extension in terminal stance. During flexion of the hip joint at TO, the role of the iliopsoas is very important. In the iliopsoas, a force is generated in late stance in eccentric contraction [29], and when the non-affected foot contacts the floor, the accumulated force is released. At TO, the iliopsoas short- ens and pulls the femur to the lumbar vertebrae. At this point, the activity of the iliopsoas pulls the trunk forward and downward, making it necessary for the trunk to act against gravity. However, the iliopsoas is characteristically shortened in hemiplegic patients. In hemiplegic patients, the iliopsoas cannot extend in late stance, which causes the pelvis and lumbar vertebrae to come closer to the femur in late stance and at TO. In addition, hemiplegic patients have frequently limitation of range at ankle and hip joint. These influence a discrepancy between the front of a trunk and the direction of a gait. Therefore, the affected middle trunk rotates to the affected side. This rotation of the middle trunk inhibits the increase of the gait speed. Consequently, speed reduces.

As a rotational malalignment of the patella, patellar tilting is subjected to the influence of the neighboring bone rota- tion other than the simple inter-relationship between the patella and its immediate neighborhood, the patellar sul- cus. Abnormal motions of the tibia and femur are believed to have an effect on patellofemoral mechanics and therefore PFPS. [13] Femoral internal rotation has been reported to be the primary contributor to lateral patellar **tilt**. [13,14] Both tibial and femoral motions have significant effects on the biomechanics of the patellofem- oral joint. With tibial rotation, the prmary effect on the patella is rotational. This pattern of motion occurs as a result of the patella being fixed to the tibia via the patellar tendon. With femoral rotation, the predominant forces acting on the patella are the bony geometry and the peri- patellar soft tissue restraints.[19]

Materials and methods: Larynges were harvested from large breed canine cadavers. With the aid of Kirschner wires placed between the centre of the vocal process and the centre of an imaginary line between the cranial thyroid fissure and the cricothyroid articulation, the mean insertion **angle** was calculated. Results: The Fast-Fix 360 delivery needle inserted intralaryngeally (n=10), according to a simplified insertion **angle** (70°), resulted in thyroid penetration (>2.5 mm from margin) in all patients. The Fast-Fix was applied unilaterally at 70° with the first toggle fired on the lateral aspect of the thyroid cartilage and inside the laryngeal cavity on retraction. The suture was tightened. Preprocedural (61.06±9.21 mm2) and postprocedural (138.37±26.12 mm2) rima glottidis cross-sectional area was significantly different (P<0.0001). The mean percentage increase in rima glottidis cross-sectional area was 125.96 per cent (±16.54 per cent).

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To analyze the collected data, the ANOVA test at 0.05 significant levels was applied. In addition, since some individual differences (e.g. typing skill, visual ability, attention level) can be nuisance factors influencing typing time, ANOVA analysis was tested using randomized block design. Participant factor was blocked. Statistical analysis suggested that there was no significant main effect on ambient illumination factor (p-value = 0.134) whereas brightness and **tilt** **angle** factors were significant (p-value =0.000 and 0.000). Fig. 4 to 6 illustrate main effect plots on the three independent factors.

Solar energy is simply the light and heat from the Sun and one type of renewable energy which also categorised as the cleanest and most abundant energy. This solar energy can be converted into thermal or electrical energy. Other than that, this energy can be harnessed for various usages, such as generating electricity, providing light, and heating system for residential or industrial use. Nowadays, new technologies are created so that people can harness the energy directly from the Sun in different ways, such as, through photovoltaic cells, solar thermal technology, and passive solar heating. From these good benefits of our new technology, a study has been made by considering solar energy to replace the battery consumption in highway dummy signal. Previously, it is proven that solar energy is more economical than using battery consumption. The initial cost might be high, but in the long term this new system is beneficial. So, this study is based on effect of various **tilt** **angle** of dummy signal on current flow and power.

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