符合HART协议的霍尔液位变送器的设计

０　引言自８０年代初智能变送器问世以来的十几年时间中,智能变送器以远远超过模拟变送器的技术性能、方便的安装和维护等优势不断地扩大在生产中的应用,开创了现场仪表的新纪元［４］。智能变送器的核心技术之一是现场总线技术,其中Ｒｏｓｅｍｏｕｎｔ公司于８０年代中期推出的ＨＡＲＴ协议现场总线标准具有兼容４～２０ｍＡ模拟信号与数字通信的性质,符合ＨＡＲＴ协议的智能变送器可以和４～２０ｍＡ模拟变送器混合使用,因此比较适合目前工业界还在大量使用４～２０ｍＡ模拟变送器的实际情况。经过１０年的发展,ＨＡＲＴ协议已成为…     

基于FF的温度变送器的研制

符合ＦＦ协议标准的现场总线仪表除了拥有常规的数字化仪表的优点之外,由于内嵌控制功能模块,可以用仪表直接构成完整的控制回路,实现传统上由ＤＣＳ、二次仪表等完成的功能,因此它还具有可靠、使用简单方便、可降低成本等优点,是今后几年数字化智能仪表的发展方向。因此,国内外都投入了很大的力量开发ＦＦ仪表,特别是从１９９８年ＦＦ基金会设立了标准测试机构以来,许多厂商纷纷开发出各自的ＦＦ产品。尽管目前符合ＦＦ标准的变送器的应用数量还不多,但预计今后几年将会大量取代传统仪表和ＨＡＲＴ仪表。国内相关单位也在积极开发…     

基金会现场总线H1的网络拓扑结构和安装布线

现场总线基金会（ＦｉｅｌｄｂｕｓＦｏｕｎｄａｔｉｏｎ,简称ＦＦ）制定的基金会现场总线（ＦＦ）是国际公认的现场总线,具有Ｈ１和Ｈ２两种总线。Ｈ２为用于制造自动化的高速总线,通信速率为１－０Ｍｂ／ｓ或２－５Ｍｂ／ｓ;Ｈ１为用于过程自动化的低速总线,通信速率为３１－２５Ｋｂ／ｓ,可以总线供电,并提供本质安全。Ｈ１产品已经问世,本文重点介绍Ｈ１的网络拓扑结构、网络组成部件和安装布线。１网络拓扑结构Ｈ１采用总线型、树型和菊花链型拓扑结构,在同一网段上可以是上述２种或３种的混合型拓扑结构,另外还有一种单点型…     

现场总线技术与现场总线控制系统

０　前言随着过程控制技术、自动化仪表技术和计算机网络技术的成熟和发展,工业控制领域又发生了一次技术变革。这次变革使传统的控制系统（如ＤＣＳ）无论在结构上还是在性能上都将发生巨大的飞跃,而这次变革的基础就是现场总线技术的产生［１］［４～５］。根据国际电工委员会（ＩＥＣ）和美国仪表协会（ＩＳＡ）的定义,现场总线是连接智能现场设备和自动化系统的数字式、双向传输、多分支结构的通信网络,它的关键标志是能支持双向、多节点、总线式的全数字通信。进入８０年代以来,各种现场总线技术开始出现,人们对传统的模拟仪表和…     

LONWORKS总线式有毒气体智能仪表的研制

介绍了一种基于ＬＯＮＷＯＲＫＳ总线的有毒气体智能仪表的工作原理、硬件电路设计和软件设计。这种智能仪表不仅具有显著、报警的功能,而且可以和ＬＯＮＷＯＲＫＳ总一或都其他ＬＯＮＷＯＲＫＳ总线智能仪表进行通信。另外,该仪表增加了用软件实现温补偿和零点补偿的功能。     

MCS—51系统多主主从通信的实现

由ＭＣＳ－ ５１ 系列单片机组成的系统, 只能实现一主多从串行异步通信。本文介绍一种由ＡＴ８９Ｃ２０５１ 单片机组成的总线控制器系统, 以实现多主主从通信     

风量测量仪表的改进设计

本文介绍风量差压变送器仪表量程更改和温度补偿在风量测量上的应用，计算出更改仪表量程和增加温度补偿的实际运算结果，证明仪表量程和温度变化对流量影响很大。     

矿山CAN总线数据采集系统的设计

介绍CAN总线数据采集系统的设计及CAN总线特点，阐述CAN通信节点的组成和通信原理；该系统在工业现场收到了预期的效果。     

氧枪喷头在使用过程中射流特性的变化及其对冶炼的影响

氧枪喷头在使用过程中射流特性的变化及其对冶炼的影响ＣＨＡＮＧＥＳＯＦＪＥＴＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＯＦＯＸＹＧＥＮＬＡＮＣＥＨＥＡＤＳＩＮＳＥＲＶＩＣＥＡＮＤＩＴＳＥＦＦＥＣＴＳＯＮＴＨＥＢＬＯＷＩＮＧＰＥＲＦＯＲＭＡＮＣＥＩＮＣＯＮＶＥＲＴＥ...     

FF总线仪表在铜冶炼DCS系统中的应用

FF总线仪表是目前国际最流行的总线型智能仪表,它与传统的智能仪表相比,在内部增加了PID控制、逻辑运算以及自诊断等功能,极大地方便了使用者的现场应用及故障处理。本文主要介绍了FF总线仪表在铜冶炼项目DeltaV DCS系统的应用过程,以及如何应用AMS设备管理系统对FF仪表进行管理和设备故障处理。     

浅析HART通讯器在仪表中的应用

介绍了HART通讯协议及275型HART通讯器的功能,并列举了HART通讯器在冶金行业现场仪表中的几种具体应用,对HART通讯器的进一步使用和推广起到了积极的作用。     

Hyperfractionated accelerated radiation therapy for non-small cell lung cancer: clinical phase I/II trial

PURPOSE: In an attempt to improve local control and survival of nonsmall cell lung cancer (NSCLC), hyperfractionated accelerated radiation therapy (HART) was carried out as a clinical phase I/II trial. METHODS AND MATERIALS: HART was delivered by 1.1 Gy/fraction, three fractions per day with intervals of 4 h and five treatment days per week. The clinical tumors were irradiated to 74.3 Gy (72.6-75.9)/66-69 fx, 33 days (29-40) (not corrected for lung density), and the subclinical lesions, to 50.0 Gy (48.4-50.6)/44-46 fx, 33 days (29-40). Sixty-nine patients with NSCLC were enrolled in this study. Nine patients were withdrawn from the study during HART due to different reasons. Sixty patients formed the study for outcome analyses. They were 57 males and 3 females with median age of 61 years (21-77). There were 41 cases of squamous cell carcinoma, 15 cases of adenocarcinoma, and 4 cases of large cell carcinoma. Overall, favorable patients (KPS > or = 70, weight loss < 5% and Stages I, II, IIIa) accounted for 73% (44 of 60) of all patients. Forty-four patients (73%) received adjuvant chemotherapy (DDP + VP16) with median cycles of 1.8 before and/or after HART. In order to compare the outcome of HART with conventional irradiation, 50 NSCLC patients treated by conventional fractionated irradiation (CFI) during the same period were chosen as the basis to evaluate relative effects of HART. They derived from the control group of another clinical trial of hyperfractionated irradiation for NSCLC in the same department. They received median tumor dose of 63.9 Gy (62.8-65.0)/34 fx (32-36), 48 days (45-53). RESULTS: 1. Acute and late complications: (a) In HART, 87% of patients (52 cases) developed acute radiation esophagitis: Grade 1-2, 46 cases (77%) and Grade 3, 6 cases (10%), at 2.5 weeks (2-3.5 weeks) after HART began. Five patients with Grade 3 esophagitis had their HART interrupted for <7 days. In CFI, esophagitis was much less (44%,p < 0.05) with 38% of Grade 1-2 and 6% of Grade 3. (b) In HART, acute pulmonary symptoms (RTOG Grade 1-2) occurred in 17% (10 cases), and acute radiation pneumonitis (Grade 3), in 8% (5 cases), while in CFI, they were 24% and 2% (p > 0.05), respectively. Late lung fibrosis (RTOG Grade 1-2) appeared in 20% (12 cases), whereas 18% in CFI (p > 0.05). (c), No other severe acute or late complications have been observed so far in HART. 2. Immediate response. In HART, 20% of patients (12 cases) achieved CR, 60% (36 cases), PR and 20% (12 cases), NR or PD. In CFI, the above three percentages were 10, 28, and 62%, respectively (p < 0.001). 3. Follow-up. The 1-, 2-, and 3-year actuarial survivals were 72, 47, and 28% for HART, and 60, 18, and 6% for CFI, respectively (p < 0.001). Better local control was seen in HART than in CFI with 1-, 2-, and 3-year local control rates being 71, 44, 29%, and 60, 20, and 5%, respectively (p = 0.001). Distant metastases developed less in HART than in CFI. The 1-, 2-, and 3-year distant metastasis rates were 23, 36, and 50% in HART, but 30, 48, and 80% in CFI (p = 0.021). CONCLUSION: 1. HART could be tolerated by most of the favorable NSCLC patients. The predominant complication was acute esophagitis. No other severe acute or late complications have been observed so far. 2. HART resulted in better survivals and local controls, and less distant metastases than CFI.     

CAN总线在质谱仪研制中的应用

质谱仪由很多模块组成,比如系统电源控制、透镜电源、数据采集以及真空测量等等,各个模块之间需要相互通讯。传统的数据通讯方式如RS232、RS485总线等,这些总线由于通讯速率、数据传输的可靠性等原因不太适合于质谱仪各个模块之间高速稳定的数据传输需要,因此,针对此不足,将工业控制领域成熟的控制器局域网(CAN)总线技术引入质谱仪的设计当中。该设计结合了ARM(Advanced RISC Machine)微处理器和高可靠性的CAN总线,在质谱仪内部既实现了点对点的数据传输,又可实现多点通讯的数据传输,最高通讯速率可达1MB/s,完全满足质谱仪器内部模块之间的通讯需求。该设计已成功用于质谱仪控制系统中,通过实验表明,该系统设计简洁、数据通讯稳定可靠。     

HART协议及在能源计量仪表中的应用

介绍了HART的优点,在上位系统和现场仪表之间建立长久连续通讯的方法,以及在能源计量仪表中扩展量程和流量的温、压补偿应用的设想,扩展了仪表的功能,解决了传统的测量方法中一系列难题.     

Vestibulo-ocular reflex function as measured with the head autorotation test

The vestibulo-ocular reflex (VOR) of 125 healthy subjects was examined over the frequency range of 0.5-5 Hz with the head autorotation test (HART). During the HART the subjects fixated at a steady target while moving their heads horizontally from side to side with increasing frequencies according to auditory signals. The gain was determined as the ratio between the amplitude of the eye and head movements in five frequency bands between 0.5 and 5 Hz. The phase difference between the eye and head movements was determined in both degrees and milliseconds. The ability to reach high-frequency bands was evaluated. The mean gain was close to unity up 5 Hz, when it decreased to 0.91. The mean phase difference showed a lead of approximately 5 degrees at frequencies below 2 Hz, and at frequencies above 2 Hz there was no phase difference within the resolution of the test. The frequency band of 5 Hz was reached by 78% of the subjects, and that of 4 Hz was reached by 94% of the subjects. In summary, the HART is a new approach with which to study VOR function and determine accurately the VOR for healthy subjects. The normal upper frequency limit is 4 Hz in the HART.     

ACN-80I DCS用于流量恒定控制

介绍我公司研制开发的已在国内稀土行业投入运行的恒流控制ＤＣＳ。该系统的空出特点是根据实际现场应用条件采用标准的ＲＳ４８５组成分布式ＤＣＳ网络，而未采用其它复杂的工业现场总线。     

基于DSP的双丝高速焊系统的CAN总线通信研究

将双丝焊技术、CAN总线技术与DSP技术有机结合,提出了一套全新的网络化双丝焊系统解决方案,并基于TMS320LF2407A进行了CAN总线通信系统规划、CAN总线通信接口电路设计、CAN总线通信协议定制等工作,试验表明该系统通信网络可稳定工作.     

Efficacy of two behavioral treatment programs for comorbid geriatric insomnia.

Older adults with comorbid insomnia and medical illness have been excluded from behavioral treatment research, but recent evidence suggested that such treatments would be effective with this population. In this study, 38 older adults with comorbid insomnia were randomized to 1 of 3 conditions: classroom cognitive-behavioral treatment (CBT), home-based audio relaxation treatment (HART), or delayed-treatment control. Compared to the control group, the CBT group had significant changes in 5 of 7 self-report measures of sleep at the 4-month follow-up. The HART group obtained significant outcomes on 3 of 7 measures. Wrist actigraphy measures and secondary-outcome measures did not yield significant findings for either treatment. Clinically significant changes at follow-up were obtained for 54% of patients in CBT, 35% in HART, and 6% in the control group when treatment dropouts were included. Although not as effective as in-person CBT, home interventions may have utility as a first-line, low-cost treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

现场总线控制系统

介绍了现场总线控制系统及ControlNet总线的通讯标准,和由ControlNet总线构成的控制系统.同时与传统的DCS进行了比较.