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無線 LAN における通信状況を調査するため，無線インターフェースのモニタ機能により無線フレームキャプチャを行い，取得したフレームを解析することで混雑状況などを推定する試みがいくつか提案されている．しかしながら，802.11ac や 802.11ax に無線環境がアップデートするに伴い，これらの規格で行われる MIMO 通信やビームフォーミングにより空間中に多重に信号が送られることとなり，また通信速度・利用帯域の増加により，無線フレームキャプチャが以前より困難になっていると予想される．本報告では，一般的な 802.11ax/802.11ac 環境において，アクセスポイントから送信される無線フレームについて，無線 LAN 設定の条件を変えながらキャプチャした際の結果について報告をおこなう．, In order to investigate the communication status of wireless LANs, several research have been proposed to estimate congestion conditions in wireless environment using wireless frame capture. However, as the wireless environment is updated to 802.11ac and 802.11ax, it is expected that wireless frame capture will become more difficult than before due to the multiple transmission of signals in the space by MIMO communication and beam-forming in these standards, as well as the increase in communication speed and bandwidth utilization. In this report, we describe the results of capturing wireless frames sent from an access point in a typical 802.11ax/802.11ac environment while changing the conditions of the wireless LAN settings.

近年では 802.11ax (WiFi6) の普及が進んでおり，旧来の 802.11ac 方式に比べ，OFDMA の採用や上り下りトラフィックの MU-MIMO 対応など多人数環境における優位性があるとされている．一方で，学校におけるオンライン授業やハイフレックス授業の増加や，授業資料およびコラボレーションツールなどのオンライン化により教室のような多人数環境で複数端末が同時に無線 LAN を使用するニーズが高まりつつある．そこで本報告では，実際の無線 LAN 環境において多数の端末が接続した際に 802.11ax がどのような優位性があるかを調べるため，以前に開発した小型シングルボードコンピュータを利用した多数端末による測定システムを 802.11ax に対応させ，旧来の 802.11ac 方式と比較した場合，および両者の方式が混在した場合について，実無線 LAN 環境において測定した結果について述べる．, In recent years, 802.11ax (WiFi6) has become increasingly popular in wireless LAN environments. Compared to the older 802.11ac system, 802.11ax is said to have advantages in multi-user environments, such as the adoption of OFDMA and support for MU-MIMO for uplink and downlink traffic. On the other hand, with the increase of online classes and high-flex classes in universities and the use of online class materials and online collaboration tools, the demand to use wireless LANs for multiple terminals simultaneously in a multi-user environment such as classrooms is increasing. In this paper, we report on the development of an 802.11ax-compatible measurement system for multiple terminals using a small single-board computer, in order to investigate the advantages of 802.11ax when many terminals are connected in an actual wireless LAN environment. We also describe the results of measurements in an actual wireless LAN environment using this system, comparing 802.11ax terminals with old 802.11ac terminals, and when both systems are used together.

近年の大学授業において，対面およびオンラインの両方のタイプの授業が混在して実施される状況が増加している．そのような場合，学生が大学でオンライン講義を受講する状況も生まれるため，大学の無線 LAN インフラは多人数でのオンライン講義の受講が可能であることが求められている．安定的な無線 LAN の提供のためには無線 LAN 環境の測定・監視が不可欠であるが，従来のような帯域測定や機器監視では中程度の帯域が連続的に発生する配信講義の品質を評価することが困難である．そこで本報告では，オンライン講義の受講品質に特化した無線 LAN 環境の測定について述べる．オンライン配信に採用されることが多い WebRTC を用いて，大規模かつ断続的に送受信試験を実施しつつ，クライアント側でアプリケーションレイヤでの品質測定をおこなうことで，従来の測定では追いきれなかった無線 LAN 環境におけるオンライン配信品質の評価および監視を実施した．, Due to the COVID-19, classes in schools have become online, hybrid, and on-demand in recent years. Various types of classes, including face-to-face classes, are now offered on campuses, and there are situations where students take online classes at school. Since students take classes using their own terminals, the university's wireless LAN infrastructure is used for communication, such as class distribution. Therefore, it is necessary to provide a stable wireless LAN infrastructure to a large number of users on campus. Operational issues for stable wireless LAN operation and measurement of the wireless LAN environment have been widely researched and developed, including detecting anomalies at the device level, bandwidth measurement at specific times, and intermittent wireless LAN environment measurement. However, today's main need for university wireless LANs is for online lectures. In this paper, we propose a new method for measuring the bandwidth of a wireless LAN in a classroom. In this paper, we describe the measurement of the quality of online lectures in a wireless LAN environment using WebRTC, which is often used for online delivery. In this paper, we describe the measurement of the wireless LAN environment specialized for the quality of online lectures. The quality of online delivery in a wireless LAN environment was evaluated and monitored.

A formal weight enumerator is a homogeneous polynomial in two variables which behaves like the Hamming weight enumerator of a self-dual linear code except that the coefficients are not necessarily non-negative integers. Chinen discovered several families of formal weight enumerators and investigated the validity of the Riemann hypothesis analogue for them. In this paper, the zeta polynomial is computed for Chinen's formal weight enumerators, and a simple criterion is given for the validity of the Riemann hypothesis analogue.

現在，学校において感染症対策の要請から様々な形態の授業が行われている．たとえば従来どおりの対面授業や，オンライン講義であったり，オンラインと対面を同時に行うハイブリッド型の授業などである．そのような様々な授業が混合して実施されている場合，キャンパス内の教室で無線LANを使用してオンライン講義を受ける状況が存在する．複数の学生が持ち込んだ端末により教室で同時にオンラインの講義を受講する場合には，その場所の無線LANインフラに十分なキャパシティが必要となる．しかし，一般的にキャンパスの無線LAN整備においては，キャパシティ設計は機器のカタログスペックや電波シミュレーションを元に行われ，実際に多数の学生が同時接続をした場合に，十分なクオリティで通信を行うことができるかは未知数である場合が多い．しかしながら，実環境において，想定する使用形態で無線LANが問題なく使えるか調査を行うためには，実際に多数の端末を用意するか，高価な計測機械や業者によるフィールドテストが必要であり，高コストである．そこで，低いコストで実環境での無線LAN環境の評価を行うため，安価なIoTコンピューティングデバイスを計測デバイスとして採用した，多数の無線クライアント接続による無線LAN環境の評価を行う計測システムを開発した．本システムにより，無線LAN環境に対し，コストを抑えつつ実環境に近い状態での計測が可能となった．, Currently, various forms of classes are being conducted in schools to meet the demands of infec- tious disease control. For example, there are traditional face-to-face lectures, online lectures, and hybrid lectures that are both online and face-to-face at the same time. When such various lectures are conducted in a mixed manner, a situation arises where students take online lectures using wireless LAN in classrooms on campus. The wireless LAN infrastructure needs to have sufficient capacity if multiple students are go- ing to attend online lectures at the same time using their own terminals. However, in general, the capacity design of campus wireless LANs is based on the catalog specifications and radio wave simulations, and it is often unknown whether the quality of communication will be sufficient when a large number of students are actually connected at the same time. Nevertheless, in order to investigate whether wireless LAN can be used without any problems in the real environment under the assumed usage, it is necessary to actually prepare a large number of terminals, or to use expensive measurement equipment and field tests by ven- dors, which is expensive. Therefore, in order to evaluate the wireless LAN environment in a real environ- ment at low cost, we have developed a measurement system that uses inexpensive IoT computing devices as components to evaluate the wireless LAN environment with a large number of wireless client connec- tions. This system makes it possible to measure the wireless LAN environment under conditions close to the real environment at a low cost.

In-Situ Vitrification (ISV) is an innovative remediation technology which melts, contaminated soil and buried wastes in-situ with electrical power to form an inert glass product. Typical processing temperature of ISV is 1, 600-2, 000°C, and the ISV technology can process simultaneously hazardous organics, inorganics (heavy metals), radioactive contaminants, and mixtures of these. The ISV treatment results in the removal or pyrolytic destruction of hazardous organic compounds, and heavy metals are either removed or permanently immobilized in a high quality, high strength, glassy residual product.The ISV process can tolerate the presence of rubble, metal, and combustible solids and liquids, and averaged volume reduction is 25-45%. The ISV is also an emerging technology for generation of vitrified underground barriers, which can be applied as a new civil engineering technology for environmental preservation.

This paper estimates the impact of generic and brand advertising on the demand for peanut butter in the U.S. An error correction model is estimated with quarterly data from 1985 to 2004 to study both the short- and long-run adjustments. The results indicate that brand advertising has a significant but short-lived effect on aggregate consumption while generic advertising has little short-run but significant long-run effects.

This paper reports results from a U.S. national telephone survey on genetically modified foods. The objectives of this paper are to determine the effect of "indifference" response on the estimate of willingness to pay and to test the assumption of common marginal utility of income among respondents.

This paper illustrates the importance of consumer segments for the estimation of the distribution of sample willingness to pay. We find evidence that those who prefer non-GM have a different marginal utility of income and that naïve pooling of consumer segments may yield a misleading recommendation for both agribusinesses and policy makers.

This paper reports results from a U.S. national telephone survey on genetically modified foods (vegetable oil, cornflakes, and salmon). The survey featured a contingent valuation in which respondents chose between the GM and non-GM alternatives with an option of indifference. The binomial and multinomial logit models yielded estimated willingness to pay (WTP) to avoid the GM alternatives. Respondents were willing to pay 20.9%, 14.8%, 28.4%, and 29.7% of the base prices to avoid GM vegetable oil, GM cornflakes, GM-fed salmon, and GM salmon, respectively. The inclusion of indifference option could increase the sample size and moderate the mean WTP.

This paper finds Taiwanese consumers' willingness to pay a premium on the non-GM food differs from their willingness to accept a discount on the GM food. It further finds that the non-GM choosers are more committed to the non-GM food than the GM choosers to the GM food.

Replaced with revised version of paper 08/05/04.

This paper presents the results of experimental auctions of the orange juice processed with the pulsed electric field (PEF) technology. A series of experimental auctions are conducted to elicit consumers' willingness to pay (WTP) for the PEF orange juice along with WTP for three other types of orange juice: unprocessed (fresh), thermally processed not-from-concentrate, and thermally processed from-concentrate orange juice. We adopt the second-price sealed-bid auction. With this auction method, the highest bidder claims the product at the price equal to the second highest bid. The auction results show that unprocessed "fresh" juice had the highest mean bidding price of $2.68/half gallon. The second-highest mean bidding price was for PEF juice at $2.48/half gallon; the third-highest was for not-from-concentrate juice at $1.95/half gallon; and the lowest was for concentrate juice at $1.31/half gallon. The bids were affected by product tasting. The mean bidding price for PEF juice dropped by nearly 17% after tasting.

This paper reports results from a pilot U.S. national telephone survey on genetically modified foods (vegetable oil, cornflake cereal, and salmon). The survey featured contingent valuation in which respondents chose between the GM and non-GM alternatives. The binary and multinomial logit models yield estimated willingness to pay to avoid the GM alternatives. Perceived risk of GM food is an important determinant of GM choice along with the price. Respondents are willing to pay 41.2%, 31.4%, 40.9%, and 52.5% of the base prices to avoid GM vegetable oil, GM cornflakes, GM-fed salmon, and GM salmon, respectively.