Evaluating the Performance of Water Chillers Equipped with Constant- or Variable-Frequency Centrifugal Compressors

The cooling coefficient of performance (COPR) and energy efficiency ratio (EER) of refrigerant R-134a compressors (single- and double-compressors) with different refrigerant tonnage (200, 250, 300, 380, 500, and 700 RT) for centrifugal and Maglev centrifugal compressors change with different operating performance load percentages (10%–100%), and constant-frequency and variable-frequency operation, resulting in performance differences. In particular, a water chiller can have a fixed cooling water inlet temperature of 32 °C and a variable cooling water inlet temperature between 18.33 °C and 32 °C. According to the actual test results, the commercial performance code program and parameter table of the water chiller were established. Based on the performance matching of different load chillers, the on-site load capacity was analyzed and the effective water chiller performance and model matching were determined as the best choice for the tonR number of the deicing machine and unit matching, providing a reference for a future large water chiller that cannot be used on site for a single unit tonR. To achieve energy-saving benefits, different types of compressors, different refrigeration tonR operation, constant-frequency unit and variable-frequency unit alternate operation, and different operating performance load percentage operation can be allocated. Finally, the results show that, when the cooling water inlet temperature is fixed, the Maglev variable-frequency centrifugal compressor water chiller is better than the constant-frequency centrifugal water chiller, and also better than the variable-frequency centrifugal water chiller. The larger the freezing tonR of the variable-frequency centrifugal water chiller, the smaller the difference between COPR and EER. When the cooling water inlet temperature changes, the Maglev variable-frequency centrifugal water chiller is better than the constant-frequency centrifugal water chiller, and it is also better than the variable-frequency centrifugal water chiller. The larger the freezing tonR of the variable-frequency centrifugal water chiller, the smaller the difference between COPR and EER. Moreover, the operating performance of the constant-frequency centrifugal water chiller is between 60% and 90%, which can maintain relatively high COPR and EER values. The operating performance of the variable-frequency centrifugal water chiller is between 40% and 70%, which can maintain relatively high COPR and EER values. Compared with the constant-frequency and variable-frequency, the Maglev variable-frequency centrifugal water chiller can maintain higher COPR and EER values when the operating performance is between 10% and 100%. When the operating performance is between 10% and 70%, it can maintain very high COPR and EER values. When the water chiller is selected in the field, the energy-saving of COPR and EER will be given priority. Therefore, the load capacity can be used to effectively manage the water chiller performance and model selection, so that the operation performance can reach the best percentage and energy saving can be achieved.

Artificial Intelligent Technique based Double-Frequency Analysis on a Single-Phase Grid-connected Inverter

Now a days more power losses can be seen in grid connected inverter. In order to reduce that double frequency in single phase grid inverter with Artificial Intelligent based fuzzy control is implemented. The inverter has two operating units High Frequency Unit (HFU) and Low Frequency Unit (LFU), low frequency reduce switching losses and high frequency suppress the symphonious currents. The fuzzy logic method expected towards deliver high yield, low total symphonious distortion, rapid response. Finally Total Symphonious Distortion (THD) contrasted among fuzzy including Integral controls (PI). The results are validated by using MATLAB/Simulink.

Russian formula of speech etiquette required to increase the communicative competence of foreign students

The article deals with the topic of studying the history of speech etiquette and address in the Russian language. Relevance of the article is caused by necessity of optimizing the process of formation of competence in foreign students in the field of history of addresses and their use in different communicative situations. In the process of communicating the address is a frequency unit of appeal, which determines the contact-establishing function. Addressing is also an important component of communication, as depending on a situation can determine its positive aspects, and may be a cause of communication problems or failure. The purpose of this article is to introduce students to the history of the first behavioral norms, rules of speech etiquette; to tell the students about possible forms of address in the Russian language; to explain to foreign students that the appeal may be considered not only as a communicative tool that serves to attract attention, but as a particularly vivid means of expression showing the attitude of the speaker towards the object of speech. The subject of research is the creation of the language picture of the world with a deep and systematic analysis of the concepts of the Russian language, mentality, traditions, customs, history, philosophy and intercultural communication based on speech etiquette and all possible forms of address. The aim of the article is to conduct a comprehensive analysis and study of the forms and possible types of addresses in the modern Russian language. The results of the study can be used in practical classes with foreign students in teaching the following academic courses: „Contemporary Russian language. Vocabulary, Development of speaking and writing”, „Practice of speech communication”, „Speech etiquette”, etc.

DOG WALKING MEDIATES THE RELATIONSHIP BETWEEN DOG OWNERSHIP AND NEIGHBORHOOD SOCIAL INTERACTION

Social interaction may be facilitated by dog ownership. We surveyed 421 pet owners about neighborhood social interactions. Dog owners also completed a dog walking questionnaire. Among adults aged 55+ (n=99; 62.2±5.6 years; 90% female), we tested our hypotheses that (1) dog owners were more likely to meet neighbors than non-dog owners, and (2) increased dog walking frequency was associated with increased neighborhood social interaction. Inverse probability weighting was used to control for differences in age and neighborhood type (rural, suburban/urban) between groups. The probability of meeting neighbors was 2.4x higher (95%CI: 1.5-3.9) for dog than cat owners, after controlling for age and neighborhood type. Among dog owners, the odds of meeting a neighbor were 1.7x higher (95%CI: 0.9-3.1) with each unit increase in dog walking frequency (unit=5walks/week). Our findings suggest that programming to support dog ownership and dog walking among older adults may help reduce social isolation.

Future iused to denote habitual actions in the vernacular of the Sirinic Zupa in the northern Sar Mountains

This paper analyzes the use of Future I to denote habitual actions in the vernacular of Sirinic. The analysis shows that Future I is a high-frequency unit when it refers to effects of what happened in the past as a custom, habit or part of a sequence. The use of Future with this meaning developed as its secondary trait, but this form was eventually suppressed from other domains of use and it was narrowed down to denoting a habitual action. The basic syntactic and semantic features of this future form with this time reference are its reference to a repeated action or a succession of events and its ability to denote the timeline of the effects of the action and its reference to wishes and commands more clearly. Furthermore, a future referring to the past is stylistically marked and thus appears as an expressive unit within the system, which is why it is typical of emotional discourse. In the Shtokavian area, Future I for habitual actions is only known in the Sirinic vernacular and in a few neighboring ones concentrated around the Sar Mountains. On the other hand, this unit is also frequent in Macedonian and Bulgarian and in some non-Slavic languages spoken in the Balkans, which is why the authors also investigate the presence of this feature in those languages.

A Design of Dual Broadband Antenna in Mobile Communication System

A design of dual broadband antenna is proposed in this paper; it consists of one low frequency unit and two high frequency units. The low frequency unit consists of a pair of printing vibrators; the high frequency unit consists of a pair of printing oscillators, which is bent at its end, and high frequency unit and low frequency unit are set on the same dielectric substrate. Through adding a parasitic unit on antenna, it can enhance frequency bandwidth without affecting the bandwidth. In the high frequency unit, it adopts gap-coupled microstrip line feeding method in order to get enough bandwidth. Through the test of dual broadband antenna, it can be found that, in the low frequency part, the antenna covers 20% bandwidth of the total bandwidth, and it covers the frequency from 800 MHz to 980 MHz. In the high frequency, the antenna covers 60% of total bandwidth and its frequency is from 1540 MHz to 2860 MHz, so the designed antenna can satisfy the frequency requirements of 2G/3G/LTE (4G) communication system.