جستجوی مقالات مرتبط با کلیدواژه « Cell Phone » در نشریات گروه « فنی و مهندسی »

In some locations, using cell phone causes interference in performance of some electronic systems. Further, certain locations require silence and information security. Cell phone blocker or jammer is a device to interrupt the connections in the mobile phone. The signal emitted by the jammer resembles the mobile signal. As a pre-requisite condition jammer should have more power than the BTS transmitter in the desired range. Under this condition, mobile signal will be zero. The purpose of this paper is to design, simulate, and fabricate mobile blocker in GSM frequency bands. The proposed device is a strong transmitter capable of producing and emitting an interference signal in the P-GSM-900, DCS-1800, and PCS-1900 bands. This signal looks like noise and interrupts the connection of cell phones within a 10 m radius of the jammer. The capability to function in various GSM bands and reduce the cost of construction are the benefits of this plan.

Sudden falls are known as the second cause of accidental injury deaths by the world health organization. In this paper effective parameters caused in human balance are analyzed in order to prevent fall. As experimental examples, effect of the parameters on human balance during standing and gaiting were investigated. For this purpose, a database is gathered. These information were recorded while 30 student balances were affected by the parameters changing in both standing and gaiting situation. In the specified pattern, the effect of vision, vestibular system and muscle strength were studied in both standing and gaiting, individually. Furthermore, in order to study the human balance while using a cell phone in gaiting, several experiments were extended. The results show the influence of the parameters on human balance. Although, men had better balance rather than women while standing but women were shown beter balanve while using a cell phone in gaiting.

Nowadays, it seems excessive use of electronic media causes sleep disorders and low academic performance in adolescents. The present study was conducted aimed to investigate the use of cell phone and its relationship with sleep quality and academic performance of second year high school students. This study was a correlation one. The statistical population was all second year high school students studying in 2015 in district one in Sari. The sample was selected 300 subjects using simple random sampling based on Krejcie and Morgan table. The research instrument includes cell phone application test, Pittsburgh Sleep Quality questionnaire and student's average (GPA). Data were analyzed using Pearson correlation test and independent t-test. The findings showed that a significant relationship was found between the use of cell phone, sleep quality and academic performance of students who have cell phones, in a way that by increasing the use of cell phone among students their sleep disorders are increased and academic performance is reduced.

The goal of this research was to investigate the evolution trend of cell phone usage in primary school children. The research method was qualitative and the type was grounded theory. The study sample included 115 girl and boy cell phone users who studied from 1st to 6th grade in primary school. The sampling of the research was purposeful. The results of the study indicated that girl and boy cell phone users at early grades of primary school، after getting acquainted with some features of cell phones (like communications، entertainment، education and services) use it positively. But at higher grades of primary school، due to lack of necessary cultural grounding in society، school and family for proper usage of cell phones، the application of cell phones gradually drifts towards improper usages (like time wasting، call disturbing، malignity، snobbery، facilitation of girls and boys relationships، SMS loves، call credit exploitation، playing with Bluetooth، disclosure of individuals'' private information، improper or pornography photos and videos applications، electronic aggression، finding hidden identity، identity disorientation، and cell phone addiction). Therefore، to avoid these issues، it is necessary for cultural and educational authorities and students’ parents to make a big effort for cultural grounding for proper and useful application of cell phones.